Unreal engine 4.21.0 becomes unresponsive if i change the engine scalability settings to "low" or "medium"

Unreal engine 4.21.0 becomes unresponsive if i change the “effects” in engine scalability settings to “low” or “medium”.

I’m having this issue in 4.21.1 as well, and the engine has to be closed via task manager. This occurs on everything including new, blank projects. i7 6700HQ, 16 GB DDR4, Geforce 1070. Will go through logs eventually.

Edit: The issue appears to have went away. I suspect it may have occurred from strange/buggy Nvidia driver behavior, as I’ve occasionally seen the engine force a shader recompile when changing basic scalability settings. (I’ve also had some builds crash with Direct3D device errors which I need to test further but also suspect that’s a driver/OS related issue
.) As of now, I can no longer reproduce the issue.

Edit: Happens on Surface Pro gen 1 as well, so probably has nothing to do with any vendor-specific drivers. Will sit and wait as suggested below.

I’m also having the same issue, but I let it sit for a couple minutes and it became responsive again. However, after becoming responsive again, the engine needed to recompile ALL shaders (even on a fresh project) which took quite a bit longer than usual.

After letting the engine compile the shaders, I tried flipping through the “effects” quality settings, as well as all other quality settings, and had no issues. I went a bit further by completely quitting the engine and restarting my machine and relaunching the same blank project and had no issues with hang or crashing when adjusting any quality setting.

If you’re still having this issue, it’s likely due to Effects quality changing - the engine will likely stall for a period of time and then have to recompile shaders.

Once you’ve compiled said shaders, this issue shouldn’t happen (or at least not hang for nearly as long.)

got same issue with 4.22, like xNITEMAREx95 and Zaggoth answered, wait a bit and let it compile all shaders then it comes back again.