Pro 2.3.3 crashes when dragging a map layer onto a group in Model Builder

[ElectraNetArcGIS]

I have a layer in a map. I have a group box on a Model Builder canvas. I dragged the layer into the group box. Pro 2.3.3 crashed. I restarted the program. I dragged the layer instead onto the canvas, outside the group box. It did not crash. I dragged the layer (expressed as a variable now) into the group box. It did not crash.

Please advise.