Windows 11 Explorer Thunderbird folders invisible

I've just replaced Windows 10 with a clean install of Windows 11 and then did a clean install of Thunderbird. No snags and Thunderbird is working fine on all my email accounts. BUT No Thunderbird folders in Windows Explorer are visible. I've looked for my Profiles folder where Thunderbird says it is but it's not there or it's invisible! Similarly there are no visible Thunderbird folders under any program folders. As my emails are working fine, none of this would matter except I do local email backups using a batch program run by Windows task scheduler so I need to be able to get to the profiles folder for this (been running fine for years under Windows 10). Also I'm curious! So, is this entirely a Thunderbird problem, or entirely a Windows 11 problem, or some interaction between the two. Any solutions? Many thanks for any help you can give. Clive