Missing php file in DMX Connect

I get the following error while inside Wappler (and a similar one on my website).

Action Step Module File does not exists! File:
@@currentSiteRoot@@/dmxConnect/modules/s3/s3.php

You can see the exact error pop up from Wappler here:

S3 was working fine for days. The php file just randomly disappeared.
How do I get it back?

Thanks!