Thanks for reporting this.
Could you please share the system info of Lightroom Classic from Help > System info > Copy & paste into a text document > upload to Creative Cloud files (https://assets.adobe.com/files) and share with us?
What type of files are you working with?
Can you please disable the graphics processor? Go to Edit > Preferences > Performance. From the Use Graphics Processor drop-down menu, select Off. Quit and relaunch Lightroom.
If this doesn't work, you can try to reset the preferences of Lightroom using the steps mentioned here: https://adobe.ly/2JSym5e
Please back up your presets prior to resetting the preferences.
Let us know how it goes.