Patch for some regressions.
Alright I'll admit I panicked a little bit.
As it turns out, Construct simply seems to no longer be able to open cloud saved files through Google Drive. Downloading the file from my Google Drive directly and opening it as a local file seemed to have resolved the issue. But that still begs the question why opening through Google Drive no longer seems to function. I'm just glad my projects aren't bricked.
The issue with Google Drive seems to persist even after refreshing my Google Login, as well as even after overwriting the project file in Google Drive itself with the successfully opened local version.
So the issue appears to be with Google Drive itself and project files that include addons, as cloud saved projects that do not involve addons still open without issue.
Is there a fix to this? I have the same problem, currently working with a local copy, but as soon as I upload it to Google drive it cannot be opened again.