First of create a date column from date and time and join it date calendar.
Date = Table[Date and Time].Date
I do not see anything like employee id, or multiple entries are for whom. I assumed Employee ID.
Try formula's like these
Max Logout Date = maxx(filter(Table,table[Task Category]="Logoff"),Table[Date and Time])
Min Login Date = minx(filter(Table,table[Task Category]="Logon"),Table[Date and Time])
Hour Diff = AVERAGEX(SUMMARIZE(Table,Date[Date],Table[Employee ID] ,"_min",[Min Login Date],"_max",[Max Logout Date]),datediff([_min],[_max],HOUR))
Thank you your effort. Unfortunately it would give me a fixed result of 9 hours. I assume it is because of the calulation in the Max logout and Min llogon date which seem to have a fixed timne as well.
I basically want to display the over hours of any day considering the min and max logon / logoff time
If you have any other ideas, I would be glad to hear them!