Is the environment set to use machine based encryption to encrypt the FSLogix VHD Files? If so, if the user is logged on to a different machine, then they would not be able to decrypt the VHD.
I am not certain of the exact configuration that "WVD with persistence profile with fslogix" refers to. Generally I would think of that as non-pooled desktops, but in that case, 1- the user should always go back to the same VM so my comment would not apply and 2- I would need to understand the reason / configuration for FSLogix.
In general, using non-persistent profiles that have been encrypted using a machine based mechanism (such as TPM) is not supported, and I suspect that this is possible the issue here.