I don't use Outlook myself but some of my clients do and one just asked what we assumed to be a simple question: Up till yesterday, she's always had a Reading Pane visible to the Right of her list of messages. Today it disappeared. How do we get it back?
The answer was indeed pretty simple and is outlined here
That left the question of why it disappeared but we'll let that ride for the time being.
The MAJOR remaining issue is that if we apply that fix, we get the Reading Pane back, as advertised. BUT, if we move to another folder and back again, the Reading Pane has disappeared again.
There are references online to the View Settings offering the option to apply a given view to all folders but the option isn't visible in our version (2019) of the software. We've also tried setting the option, then closing and re-opening Outlook to see if the setting survives program restart. It doesn't.
I could find no references to this issue online, which suggests it is not normal or even common behaviour. So, presumably, the settings should behave as we'd expect - Remain until changed; like in virtually all modern software.
To further complicate the issue, the client is using identical versions of Office 2019 on two identical workstations both running Windows 10 Pro 21H1. And both started simultaneously displaying this aberrant behaviour yesterday.
First thought, natch, "Windows Update".
Not possible in this case. Both systems have Horizon Datasys Rollback installed, which has, since V11.2, provided the option to block Windows updates so that we can choose when to permit them and neither machine is currently permitting any updates.
That leaves the more worrying possibility. The only other thing which must be common to both workstations is that she accesses the same email account (her own) on both systems so perhaps one of the half dozen emails she received yesterday (all from long standing trusted clients of their own) has inadvertently included some kind of malware, or, more innocently, some kind of broken attachment which has triggered a bug in Outlook on both systems. I'm about to start scanning those messages for signs of deliberate malice but if it's not deliberate, it might not show up in any scans.
Anyone got any better ideas?