Be aware that Monterey has substantially restricted application abilities to prevent malicious use. I wonder if you are using a version of MRIcroGL that predates this operating system?

1. Are you using v1.2.20220720?
  https://github.com/rordenlab/MRIcroGL/re...


2. What is the output when you select the About box, in particular I am curious about the CPU and GPU you are using. Can you please copy the whole text, it should look like this:

1.2.20220720 Cocoa ARM64 LLVM
Author: Chris Rorden
License: BSD 2-Clause
Version 11.6.5 (Build 20G527) MacBookAir10,1
Retina Scale: 1
Apple; OpenGL= 2.1 Metal - 71.7.1; Shader=1.20
2.1 Max 3D texture: 2048
Current texture: 155×193×200 23mb