Hi Adam,
what does it mean when a view is Read Locked?
It means that the view cannot be modified because it is write-protected. Since PixInsight is a strongly multithreaded environment, a process must lock a view before attempting to process its image. While the view is locked, no other process can modify it. When the process has finished processing the image, it must unlock the view. Of course, no standard process leaves locked views; doing that is a serious error.
This is indeed a small bug in the ChannelCombination tool. I discovered it yesterday, but the installation packages were already on the server (and the macOS packages were already notarized by Apple, which is a pain in...), so I decided to leave it unfixed. This bug is completely innocuous. The view is not locked, it's just the window title that is not updated correctly after the new image has been generated by ChannelCombination. If you simply zoom in/out the image, the title will be updated. Sorry for the inconvenience, I'll fix this as soon as possible (although with low priority).