I’ve found that the Pyramid works fine with everything I send it to and if there is an issue, it’s with the receiving device. Now that said you may need to make some settings on both devices to have the RC300 happy to play nice. The most important one for the Pyramid is to ensure it’s sending clock (tempo) to the RC300. You do this in the MIDI OUT settings menu. There is a setting to turn on MIDI sync send on each MIDI output. Turn on one or both of these. Make sure that if you only turn on one that it is the output you connect to your RC300. Next you have to tell the RC300 that it’s a slave and to not use it’s internal clock. Check it’s manual on how to do that. Hope this helps.