Simple includes mask problem - should be easy

I'm using the 'Keep remote directory up to date' function and would like it to watch all PHP files inside some subdirectories named 'watch'. The current working directory is set to dir on the local and remote sides.

My folder structure is:
I'd like it to watch for changes to *.php files only inside the two directories named watch. I've tried the following include masks but none work:

• /*/watch/; /*/*/watch/; *.php
  
• /*/*/watch/*.php
  
• /subdir1/watch/; /subdir2/subsubdir1/watch/; *.php
  

I'm especially confused why the third mask won't work.

Can anyone suggest an include mask which might work?

Using WinSCP 4.1.8.

This is not an easy task. Basically WinSCP traverses the local directory structure and omits any folder that is not included in the mask. So you need to make sure all parent folders (down from the root folder of synchronization) are included, but no files within them, except for subfolders you intend to synchronize.

See https://winscp.net/eng/docs/file_mask#path