iPadOS 14.7 mail not synching

Since updating to iPadOS 14.7 mail is not synching (even though it says it is). Messages read and/or deleted on Mac (Big Sur 11.5) or iPhone (iOS 14.7) are not synching.
iPad mail shows read messages as unread and does not delete messages deleted elsewhere - same result whether manual or timed synch. Same result after power cycle.
iOS 14.7 on iPhone works correctly (reflects action on Big Sur).
Mail is from Exchange server using Outlook. Just for interest I launched Big Sur mail - the update had disabled my main Exchange account; when re-enabled it matches Outlook as does Apple mail on a non-beta iPad mini.
It is just the iPad that does not synch reads and incoming deletes (it receives new mail). Messages deleted on iPad are correctly synched elsewhere.
Anyone else seeing similar issues?