It happens suddenly - every attempt to connect or route finish with track that has no net (Null Net and Line to SMD spacing error). It also want to start route from specific layer (in my case layer 5), even I am selected Top layer.
I try few things, check constraint manager, grids, route options, updating netlist, dehighlight all - but with no success. Since I am saving regular copies on every step, and older copy before few hours works normally, but current design just driving me nuts.
Any ideas? I am running version 16.6 s050 - I new there is hotfixes available, but just want to know if it is something I just enable by mistake.