I use mail clients Gmail on Android and Thunderbird on Windows both linked to my Zoho mail account via imap and smtp.  Both work fine except only Thunderbird will open the Spam folder. In Gmail trying to open the Spam folder shows the busy icon for a few seconds then just goes back to displaying Inbox.

In Zoho webmail I tried switching off View in IMAP Client for the Spam folder to see what would happen and that caused Gmail to tell me the spam folder was empty. Switching  View in IMAP Client  back on again returned to the original behaviour.

Any ideas how I can see the Spam messages in Gmail?