While troubleshooting this issue, I found that the plugins in the issue have problems with their custom update systems.
- First, I went to the child site and noticed that WP itself doesn’t detect available updates for these 2 plugins. At this point, MainWP Dashboard could not detect these updates since they are not detected by WP.
- Next, I forced WP to recheck for updates by refreshing the WP Admin > Updates page in the child site.
- Once WP detected updates for these plugins, I synced the site and updates showed up in MainWP.
In short, this is a bug with the custom update mechanism that these premium plugins use.
We found that the problem was in the custom code that was used in the Custom Dashboard extension, not the actual extension.