Run TB in safe mode (hold Shift when you launch TB) and see if it makes any difference. Note also that when you click Get Messages, only the currently selected account is checked; click the drop-down to check a specific account or Get All New Messages (Shift+F5). The setting isn't present for folders that are automatically checked, such as Inbox. See the attached picture for the Properties window for a user-created folder. If these methods do not work, then contact the support team of your email provider. So, here are the solutions you solve the problem of the IMAP folder not syncing.

Why IMAP Folder is Not Properly Syncing?

While these solutions work, there is are chance that it will happen again. To avoid that, you have to take some precautionary steps. Subscribing to a folder makes it appear in the Folder Pane, but one might not always want Outlook Login Issues Troubleshooting a folder to be synced automatically if it is mainly an archive folder or one that seldom receives new mail. This limits the amount of network traffic and improves performance for syncing important folders. You should look at your Outlook desktop client settings to review the default synchronization schedule and tweak anything you can to get it to poll Google's IMAP servers more frequently. I access the IMAP servers from 3 different machines, and they all see the changes from each other.

Chosen Solution

Suspect some Apple Dev's have been lazy with some code fix outlook not Opening after windows update in IOS18's mail.app and its causing the issue. I was a little hesitant but went ahead and let it completely remove all the synced items from the account off of my iPhone. After a minute, it was removed so just went and re-added it and BOOM. Decided to just try completely removing my Gmail account, the one that wasn’t syncing with the Mail App after the iOS 18 update.

IMAP folder sync issue in the new Outlook (moved emails not syncing to webmail)

When you synchronize mail using IMAP between Gmail and a desktop mail client such as Outlook, there is a necessary delay between changes made independently at both ends being synchronized in both directions. When you are accessing Gmail via the web application everything is hosted on Google's cloud servers. So it must be something in IMAP protocol handling on the old server that makes the iOS Mail app go out of sync or crash the syncing mechanism on the iOS device. Maybe some encoding behavior or just a different linefeed or something that has changed over the years... Otherwise why even have the ability to auto-sync? If I need to click on each folder to force the sync/download from server then auto sync serves no purpose.

• Meanwhile, the "connecting" or "Checking for mail..." just stays on the bottom status bar of the mail app.
• I will try the safe starts and experiment with the buttons ans see if it improves.
• My VPN was working in the background, even though the file was closed.
• After instalation ios 18 all my accounts in mail app stopped to sync( including icloud mail).

My accounts in Mail app stopped to sync post update

I am also running QuickFolders and its the same nothing shows up on those tabs until i physically click on them. Ok so my mistake the Properties option is there when right Diagnose Office Activation Conflicts clicking folder - I was only focused on right clicking on the email address to take me to server setting I was not clicking on the actual folder. I right click a folder and Properties and it take me to attached windows. I don't see - 'When getting new messages...

Get email updates

I checked all 5 of the tabs in this window that expressions is not there. This seems bizarre the email would not populate. A stable connection between your email client and email server depends on the syncing of your IMAP folder.