since 2.81a are near to be 3 versions, 2.82, 2.83.x and in one more than one week 2.90 and not only on an earlier release.
You have check for already report bug in developer.blender.org ?
If you have same problem in 2.90BETA you need (should /must) make one good bug report (if not already made from other, i doubt on this), this problem can be one bug that stop Blender 2.90 to be released until fixed.
You have problem to enable OpenCL hardware in OpenCL preferences or what?
OpenCL hardware still not working with default setting and after re-set Preferences to use it? not working and has stopped working are too generic to have proper reply