A winner first post... Internet Explorer not remembering Forms-based (i.e., AutoComplete) passwords for a website after the Citrix VDA has been restarted, or if I log into a different server.
This was a real pain for some of my users that I didn't pick up on during the testing phase of deploying UPM (because I don't generally save passwords for websites I go to, I remember them... but that's another story) and caused a few swears & tears when it took me a few days to resolve.
Internet Explorer (I'm working with v11 and up on Server 2012 R2, XenApp 7.6 published desktops, UPM 5.2) remembers passwords in two ways - the Username/Password popup box that it displays when presented with an HTTP 401 challenge - these are stored as Generic Credentials in the Windows Credential Manager.
The other way it can store passwords is via an AutoComplete form.
According to Nirsoft, the HTTP Auth passwords are stored in AppData\Roaming\Credentials and the forms-based auth passwords are stored in HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IntelliForms\Storage2. I couldn't quite match this up with what was happening in my environment, but using this post (and after restarting my VDAs) I was able to get the "Web Credentials" section of Credential Manager to roam to different servers & persist after a reboot.
In summary, configure the following Citrix Profile Manager policies:
Directories to Synchronize:
Folders to Mirror:
Process Internet Cookies at Logoff: