I think that I do recall a similar issue, when I checked my account with VC. Like you, I thought that it was a glitch. So, I waited a day or two. Then, the funds were there again. I had trust with USAA. Now, I have been passed off to a company that I was not aware; and one that I may not would even choose. At least, we could have been assisted with a transfer to a custodian of our choice. But, I guess USAA would not have received a kickback for that?
This does sound strange.
If you have access to your Victory Capital Statements, you should be able to see the activity for any credits or debits. Also, check your USAA bank account statements during that monthly cycle to see if perhaps the funds were moved to your deposit account.
~ Lori C