Intellij auto-closes any file outside of the project

Hello,

 

I have been using Intellij for a while, and sometime around June I noticed a problem where if I opened a file outside of my current project (because Intellij is a great editor, and of course I want to use it) Intellij will auto-close that file for me without my permission when I try to do anything in that file. If I open the file in it's own project, I can edit it, but this process is very inconvenent, as opening a new project takes longer than opening a single file.

 

Things I have tried:
Invalidate caches and restart
Re-install

Update

Drag-and-drop open the file

File->Open the file inside of Intellij

Having no other tabs open when I try to open the file

 

This has been extremely aggravating for me, and I am unsure of where to even begin debugging. 

 

Any advice would be appreciated, thanks

Information about my Intellij:
```

IntelliJ IDEA 2021.1.3 (Ultimate Edition)

Build #IU-211.7628.21, built on June 29, 2021
Licensed to <Redacted>

Runtime version: 11.0.11+9-b1341.60 x86_64

VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
macOS 11.5.2
GC: ParNew, ConcurrentMarkSweep
Memory: 1979M
Cores: 16
Non-Bundled Plugins: org.intellij.plugins.hcl (0.7.10), some.awesome (1.14), String Manipulation (8.15.203.000.3), org.jetbrains.plugins.ruby (211.7628.1)
Kotlin: 211-1.4.32-release-IJ7628.19

```