Are you exporting as ASPiK and building with the proper VST3 SDK?

I am currently working on ASPiK 1.6.8 with VST3 SDK 3.7.2 support, but I've had no issues with the current release building for VST, AU and AAX.

In addition the VST3 builds include the VST validator, so if the plugin builds as a VST3, it has successfully passed all validation criteria and should not crash any host.

If you are using RackAFX6 and the legacy projects, then trying to rename the RackAFX plugin as .vst3 then that won't work and is long un-supported.

Will 

I am finishing work on the new ASPiK and RackAFX, using VSTSDK 3.7.2 and its included new VSTGUI4.10.

During this development, I found that the new VSTGUI4.10 package has a significant change in the way the library is initialized. I had to add code to the plugingui object to overcome this new addition/change, and had to make changes in each of the plugin shell GUI objects to accommodate. 

The result of the new VSTGUI4.10 initialization was that compiling previous ASPiK versions with it caused the plugin to crash the DAW as soon as it was opened (AU, AAX and VST since they all use the same library). This was from the VSTGUI4 change, and had nothing to do with ASPiK (which is the case, 99.99999% of the time).

It is important to only use the SDK versions that are stated on the ASPiK and RackAFX download pages - the most problematic for me is VST3/VSTGUI4 in which the designers often make severe changes that will break their own (and my) older plugin code. 

Will