We have users using PST and since they are huge we have enabled client drive redirection and map the pst using this option. We found that the client drives are auto-disconnected in certain cases and couldn't find the root cause this issue.
I did not see this issue when opening a redirected folder on remote desktop that containing some .pst files. Is this your case? That would be helpful to do more investigation if you could provide the following info:
1. The reproduce steps
2. Related logs on both client and agent
3. Upload the .pst file that caused this issue