Thunderbird IMAP Folder Synchs

Does anyone have experience with Thunderbird and Disroot? I been using POP, so that all emails stay local once downloaded. I figured I try IMAP to test synchronizations (and then can copy emails to an unsynch folder to stay offline). In my testing though, I can not get folders to synch. I create two on the mail.disroot page (even clicked subscribe as some other non-Disroot-email topics showed), but none come in Thunderbird. I created a folder in Thunderbird, and that does not go to the web side. The only things that synch are emails in INBOX. And, for some reason, during test those emails were lost and nowhere to be found on either end (thankfully, these just test emails). Hmm, with that last comment, what if using IMAP will cause important emails lost?
Welp, if anyone has experience in getting folders synching between Disroot and Thunderbiurd using IMAP, please let me know.
Thank you.