To confirm, I am having the same exact issue. Oculus software version 15, Bedrock 1.16.200, Windows 10 20H2 update. Other games still working, this one crashes on "Checking for updates".
I have also tried using the launch link: minecraft://mode/?OpenXR=true, but that doesn't appear to launch correctly either. It results in an error pop-up in Windows that says "File system error (-2147219196)."
I am having the same problem. Everything was fine and now it is not. I am very confused at the whole “Enabled earning Achievements while playing in a world with Add-Ons applied”. First when can we expect a resolution to this, After spending money in the marketplace to enhance my gameplay now seeing that the achievements would still be enabled after the 1.21.70 update I was very excited, right up until I realized I am indeed NOT getting achievements and the achievements in my world were disabled because of a resource or behavior pack purchased directly from the Mojang/Minecraft bedrock marketplace. I have been played for a Realm for my daughter and I for over 2 years and now that world is as if we played creative disabling the achievements for us. I am furious. When can we expect a resolution to this issue?