bedmesh not applying at all for first layer?

My company bought the idex vcore 4 500 to prototype large parts, but suddenly it does not want to use the mesh when doing first layers. it probes before ach print but no matter if i do small or large prints that spann the entire bed. when i did a 400x400 1 layer test i had to turn flowrate down to 80%, it unmderextruded where my blue sides are on the bed and overextruded in the middle. were having huge problems with general bad extrusion as well.. Any insight would be extremely valueable. its all stock ratrig, using newest prusaslicer profiles for 0.6mm. The printed worked fine in the beginning but now almost all aspects of quality seem to degrade.