No it is not affecting the start and end time, but it might be having an impact on the start date. I am making an assumption you have checked the obvious but perhaps not, you need to look at the route and the capacity and any multi-level impact.
Hello Sanax, I would recomend you to look the settings of the operation no.10: what is your relation between the Run time, the Process Qty. and the Hours/time factor. The message is saying that for the quantity you want to produce for item 56864540 in that operation, it will takes more than 100 days.
Yes as you said we can not enter more than the group qty., but this may happen when you imported the data. so it is better he can check the work center qty. also.