I experience frequent crashes in 1.8.4 when opening a specific model. Model & crash report attached. When I manage to open the model everything works fine and as expected. This has never happened in 1.8.3, so it may be due to the version change or to some some coincidental change in the model.
If the model is corrupt I would expect a repair option or some instruction how to repair it. I would certainly not expect the software to crash.
crashreport AP 1.8.4.txt
Kartonmodell Ladenzeile KüKo.afpub