You are apparently unaware that muster rolls comprise the bulk of Confederate Compiled Service Records, and that relatively few negroes were regularly mustered into the service. The overwhelming majority of negroes were employed (if free) or impressed (if slave) as civilian employees. Only those who were actually mustered into the service are recorded on muster rolls, and I have found both freemen and slaves on some of the several hundred CSR microfilms I have transcribed over the years; however, as I previously stated, relatively few negroes were actually mustered into the service. If you want to find negroes, with rare exceptions you don't look in the Compiled Service Records. They weren't "sanitized" in some bizarre conspiracy to rewrite history; they were never there to begin with because they never belonged there -- they were employed, not enlisted and mustered. If you still believe that the Compiled Service Records have been edited to make them politically correct, or to aid in some kind of 20th century cover-up, then you don't know anything about the CSRs.
Here's the policy on the employment of negroes, from A DIGEST OF THE MILITARY AND NAVAL LAWS OF THE CONFEDERATE STATES, FROM THE COMMENCEMENT OF THE PROVISIONAL CONGRESS TO THE END OF THE FIRST CONGRESS UNDER THE PERMANENT CONSTITUTION.
XI. EMPLOYMENT OF NEGROES.
177. Whereas the efficiency of the army is greatly diminished by the withdrawal from the ranks of able-bodied soldiers to act as teamsters, and in various other capacities in which free negroes and slaves might be advantageously employed: Therefore,
The Congress of the Confederate States of America do enact, That all male free negroes and other free persons of color, not including those who are free under the Treaty of Paris of 1803, or under the Treaty of Spain of 1819, resident in the Confederate States, between the ages of eighteen and fifty years, shall be held liable to perform such duties with the army, or in connection with the military defences of the country, in the way of work upon fortifications or in government works for the production or preparation of materials of war, or in military hospitals, as the Secretary of War or the commanding general of the trans-Mississippi department may from time to time prescribe; and while engaged in the performance of such duties shall receive rations and clothing, and compensation at the rate of eleven dollars a month, under such rules and regulations as the said Secretary may establish: Provided, That the Secretary of War or the commanding general of the trans-Mississippi department, with the approval of the President, may exempt from the operations of this act such free negroes as the interests of the country may require should be exempted, or such as he may think proper to exempt on grounds of justice, equity, or necessity.
178. That the Secretary of War is hereby authorized to employ, for duties similar to those indicated in the preceding section of this act, as many male negro slaves, not to exceed twenty thousand, as in his judgment the wants of the service may require, furnishing them, while so employed, with proper rations and clothing, under rules and regulations to be established by him, and paying to the owners of said slaves such wages as may be agreed upon with said owners for their use and service; and in the event of the loss of any slaves while so employed, by the act of the enemy, or by escape to the enemy, or by death inflicted by the enemy, or by disease contracted while in any service required of said slaves, then the owners of the same shall be entitled to receive the full value of such slaves, to be ascertained by agreement or by appraisement, under the law regulating impressments, to be paid under such rules and regulations as the Secretary of War may establish.
179. That when the Secretary of War shall be unable to procure the services of slaves in any military department in sufficient numbers for the necessities of the department, upon the terms and conditions set forth in the preceding section, then he is hereby authorized to impress the services of as many male slaves, not to exceed twenty thousand, as may be required, from time to time, to discharge the duties indicated in the first section of this act, according to the laws regulating the impressment of slaves in other cases: Provided, That slaves so impressed shall, while employed, receive the same rations and clothing, in kind and quantity, as slaves regularly hired from their owners, and in the event of their loss, shall be paid for in the same manner, and under the same rules established by the said impressment laws: Provided, That if the owner have but one male slave between the ages of eighteen and fifty, he shall not be impressed against the will of said owner: Provided, further, that free negroes shall be first impressed, and if there should be a deficiency, it shall be supplied by the impressment of slaves according to the foregoing provisions: Provided, further, That in making the impressment not more than one of every five male slaves between the ages of eighteen and forty-five shall be taken from any owner, care being taken to allow in each case a credit for all slaves who may have been already impressed under this act, and who are still in service, or have died, or been lost while in service. And all impressments under this act shall be taken in equal ratio from all owners in the same locality, city, county, or district.