For about 1 month have been unable to edit the notes (body) of about 10% of contacts on different pcs, different profiles, same Office 365 account. Turning off cached mode made no difference. New profiles didn't help. Forcing reversion from Monthly fast channel to semi-annual didn't help either.
Not getting problem in the cloud Outlook.
Local workaround was to create new contact and copy/paste the body into the new one, then delete old contact. Didn't seem to recur on new contact.
3rd tech found it in the known issues the other day.