How to reproduce:
1. grant an advancement and wait a little bit, (or hit escape to force save the data)
2. run these 2 commands in quick succession: /advancement revoke @s only <granted advancement> then /reload
3. open your advancement menu, you will see the advancement was not revoked, and thus can be re-revoked using the same command.
(might need to repeat the steps if it doesn't work.

What happens (most likely):

• Advancement revoke does not get written to disk before the advancements are reloaded.
• The /reload will interrupt the game before it can save the revoked advancement.

What should happen:

• The advancements that have been revoked between now and before /reload is executed should be saved to disk.

Below a video containing the process with the steps clearly shown:
https://www.youtube.com/watch?v=nnQrng0_xk8