5.802 won't sync Samsung S21+ Android 11

I have background sync set to ‘always’ in General settings/Network.

In the account I want to sync I have Folder poll frequency set to 2 hours for 1st and 2nd Class folders and Push folders set to 1st and 2nd Class folders, but it doesn’t sync.

I noticed that K-9 isn’t set up in the Manage accounts list on the phone, Auto sync data is set to ‘on’. K-9 isn’t listed in the drop down list of additional accounts so that I could add it.

Suggestions for what I am doing wrong please.