Yep, MIDI Solutions stuff relies on power through the MIDI cable. I don't like that, because it's using the voltage diff between the MIDI signal lines and the the MIDI ground, and stealing power from the data signal. Some setups will work with it without a hitch, but some won't. If no one chimes in who owns one and a Stomp to test it, you could check the MIDI cable pins with a volt meter coming out of the Stomp and see if its providing enough power (~ 5V). Look online to figure out which pins to check. And make sure you have a money-back guarantee if you buy the solution in case it sucks. I sent mine back because it didn't work with half of my stuff.
If it doesn't work, I found and bought this PCB board for $15
https://midisizer.com/midithru/midithru-original/
which provides 5 outputs compared to the MIDI Solutions 2,
and ordered the parts listed in the Bill of Materials (there aren't very many of them and you can get them cheap from online electronics stores like Mouser or DigiKey). I can't remember my total cost, but it was around $35. Its a simple project, and if you know how to solder, you're good to go. If not, ask your geeky friend. You'll end up with 1 MIDI input, and the unit splits that into 5 MIDI outputs. It uses an external power supply (wall wart kind). It works flawlessly, and I've used it for years.