Due to recent system updates by Apple that have tightened permissions, users are temporarily unable to add local external subtitles as before. We will fix this issue shortly.
The good news is that, in the meantime, you can still load local external subtitles using a few methods.
You simply need to place both the video file and the subtitle file in the root directory of the Moon Player folder, as shown in the image below:
Then, you can load the external subtitles as usual.