Strange thing is happening... bug?

[ViciousMegZ]

Hello everybody!
I've been playing on a mod map (Hagenstedt) for a while now and all of a sudden my workers won't listen. I place them on the corner of a field (like always), same spot as usual, and now they won't start. So i go to the opposite side of the field and then they start, but they then leave part of the field (where I wanted them to start earlier) without sowing it... I combined field 14, 15 and 16 and that worked just fine... until today. Can anyone tell me what's going on?
Also, I tried getting a screenshot but failed...

[Avegooday]

Perhaps this particular spot have some leftovers from previous harvest and is not ready for seeding. If you look at the "state" of the field on the right panel, does it show it has been plowed if needed (may need to zoom on that part to be sure) and have you tried to pass a cultivator again in this section (sorry for my English, not my 1st language). Also, you say the workers won't start but are you able to do it yourself ?