Trouble playing notes simultaneously

I'm currently having an issue with Reaper not letting notes play simultaneously. Only 1 of the keys seems to play when all notes timed together. When some notes are moved slightly out of timing in the Chord, then all those notes play. I screen-recorded the issue and provided in link below

Might perhaps be related to the plugin. What's the name of the plugin loaded on the Track? And have you also already tried if the behavior is the same when playing the chord with a different plugin?

The plugin being used in the screen record is Kontakt. I've tried multiple third party plugins on Reaper; DSK, Kontakt, Ample, and Spitfire. All have the same issue in Reaper. Then tested using just Kontakt platform, no issue playing simultaneously notes inside Kontakt.

Hi Xephalos, in Kontakt, in Settings or Preferences, or similar, is there exist something like Global Polyphony setting? Edit: I am sorry Xephalos, I did not notice you mentioned you have the same problem with the other VSTi. Do you have some pre FX on your track?

It's all good, no pre-FX. I did just discover that I'm not having this issue when using Reaper on my old ASUS Laptop. The old laptop uses a Realtek sound driver, whereas my current HP desktop uses an AMD sound driver. This may be an incompatible sound driver issue. Also, Kontakt states it has a "standalone" app, which I'm assuming is their Komplete Control app, and it doesn't actually have a DAW

RESOLVED 

Start Menu > Reaper Folder > Reaper (reset configuration to factory defaults) I'm sorry, I didn't end up figuring out exactly what caused the issue. This factory reset fixed it though. Thank you for assisting me, I really appreciate how quick the responses are in here. :-)