I had posted this in a pre-release-thread, but I repost it here, so it doesn't get lost.
There seems to be a problem with the API-function GetAudioDeviceInfo.
When I enter a faulty samplerate in WASAPI, it doesn't return device-infos anymore, even if I change to a valid one, like ASIO.
It needs a restart to work again, but only, if I choose a different device than WASAPI. Otherwise, it keeps continuing not to work.
I would expect it to always return the device information, even if it contains "illegal"-settings.
Don't know if it's a regression or if it had been in previous versions too.
Tested on Windows 7, Reaper 5.983rc3(x64), but I suspect, it's still in the final 5.983.
Here is a LiceCap about that: