We are using Horizon 7.13.0 and publishing Instant Clone pools. One pool that we have been using has users sometimes logging in and getting "The User Profile Service service failed the sign-in. User Profile cannot be loaded." with an OK button that closes the session when the user hits it. Any user that tries to login to this VM gets this error. Other machines that are cloned from the same CP-parent machine will work correctly.
After some investigation, i found that the C:\users folder is empty on the machine that gives this error. If I copy a Default folder from C:\users on a working VM users can then login to the machine with no issues.
Any ideas what could cause this?