I really like the model with the t-tops.
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OK, sorry. I'm assuming you uninstalled/reinstalled your firewall and anti-virus but left Adobe/Thunderbird alone, the same as they had been before? Have you checked your firewall settings to make sure that port 993 is opened (either open generally or configured to allow connections for Thunderbird)? If you haven't changed anything with your Adobe or Thunderbird settings I don't see why POP vs. IMAP would matter. Assuming you didn't make any changes to Adobe/Thunderbird when you reinstalled your firewall the answer is almost definitely going to be inside the firewall/antivirus settings.
Edit: In fact, the IMAP instructions also indicate that you need to open port 993 so that is where I would start.