Hello,
i realized all version of affinity designer crash when the app is running on integrated graphic card like Intel HD4600 in my case. I really don't know if the problem causing the designer or driver in Windows 10. I installed latest driver version for this GPU (part of my Core i7 4810HQ CPU in Acer Aspire Nitro V15) and it didn't fix this. There is no solution if you have no separated GPU. I have the Nvidia 860M, so i switch Intel HD to Nvidia 860M in Nvidia Control Panel and it works perfectly stable.
For those who experience the same issue, try it, it should help.
Tomas