System Information
Operating system: macOS-11.5.2-x86_64-i386-64bit 64 Bits
Graphics card: NVIDIA GeForce GT 750M OpenGL Engine NVIDIA Corporation 4.1 NVIDIA-16.0.13

Blender Version
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-10-16 12:26, hash: rB4a00faca1a5e
Broken: version: 2.93 LTS

Short description of error
When a text object has a Library Override applied the text object remains un-editable

Exact steps for others to reproduce the error
A text object exists within a collection within a file - let's call this _Original.blend

A new .blend file is created - New.blend

Steps: File > Link... (locate Original.blend, locate Collection) then Link.
The file is linked successfully.

Steps: Select the Text object; Object > Relations > Make Library Override
Library Override successfully applied

Steps: Select the text object, TAB to Edit
Pop-up message:
Report: Error
Unable to execute 'Toggle Edit Mode', error changing modes

Thanks! You guys are doing an amazing job. You are the backbone of how Blender becomes as awesome as it is. Keep up the great work! We're all looking forward to the official release of 3.0. :)