No problem here either. iMac. 27-inch, Quad-Core, 16 GB Ram. What seems to be happening?
Can you try maybe copy the page and select all dotes?
Sorry to hear about this trouble and delayed response. The file you shared is working fine at our end. We have recently released an update for InDesign 2020 (v15.1.1) which contains some stability fixes. If you are not already on (v15.1.1), then we recommend you to update to the latest version and let us know how it goes.
If that doesn't help, you may also try resetting InDesign preferences. Preference settings are saved each time you quit the application. Crashing and unexpected behavior in application can be caused due to corrupt/ damaged preferences. Please follow these steps and let us know how it goes:
Please note that resetting preferences will remove all the custom settings and InDesign will launch with default settings. This way all your old settings will be saved in .old folders and InDesign will recreate new folders with default settings.