After a power outage (possibly complete coincidence but suspicious) Outlook 365 (desktop version) on 3 different Windows 10 machines (same Windows account), will load but not display HTML emails. Non HTML mails are ok. I only see the first line of HTML messages. This affects several different email accounts from different providers. When I look at webmail or my phone email the same mails look ok. Switching to a different network (eg use Wi-Fi over my 3G connection) makes no difference.
It seems to be related to my Windows account in some way but I am mystified as to what setting. It does not seem to be the basic Outlook security setting that stops loading HTML mails. Even with that off (so it should load HTML) only a small part of the email loads. In some cases the images load then immediately disappear, as if being hidden, leaving a white space. The same email account works ok on Outlook on another PC that does not share the same Windows logon.