I just installed SMAPI in Manjaro and Solus and have the exactly same issue in both. After installing SMAPI and try to launch Stardew Valley through Steam it says "running" for a few seconds and then just back to normal without launching anything nor showing a message.

Before the update I had a previous version of SMAPI on Solus that worked well (2.5.4), but not in Manjaro (I couldn't install it). I uninstalled it before try 1.3 beta and everything was okay in both OS, and also everything works again after uninstalling SMAPI again. I've also reinstalled SMAPI a few times and it's the same.

@anakcj Can you come ask on Discord? I'll need you to run some tests to figure out why that's happening for you.