Since moving to ArcGIS 10.6 from 10.5, ArcMap is crashing on various edits to new and existing models. It often crashes on connecting a layer to a process in Model Builder. It happens both with layers dragged in from the ArcMap table of contents and with layers created in the model with MakeLayer It does not seem to happen on connecting a feature class to a process. I installed the TLS 1.2 patch that that did not make a difference.
Windows 10
16 GB RAM
64-bit
ArcGIS 10.6.1.9270
Laptop computer
NVIDIA Quadro M 10000M display adapter
Updating the NVIDIA driver seems to have fixed this