Webio,

First, what timezone is the server, client machine, and user account set to?  Second, how are you adding the hour component to a task in Outlook?  According to Microsoft documentation tasks do not have a time component from within Outlook itself.  Third, I am actually seeing the opposite effect: when I set the date-time component in webmail to be 31 Jan 14:30 (MST) when it syncs to Outlook in shows on 30 Jan.

They are all UTC+1. When it comes to hours I will let you know today since this was reported by my customer and tested and reproduced by my employee.

Ok so this is weird. Outlook just like you said does not allow to create any hour for task days (so my mistake). But take a look at screenshot. Task added now (24.01.2019) about 9:40 (UTC+1) for tomorrow is visible as today task which will start on 23:00 (also UTC+1 on webmail and server). So as you can see task added for tomorrow in webmail is visible as task for today and task added for day after tomorrow is visible as task added for tomorrow (also 23:00).

Any news regarding resolving this issue?

So ... my client asks about this again and I must forward this question here: any news?