In Mosaic Designer v2.6.x I'm using the "Send Paradigm Action" and type Channel Set Intensity on a trigger, to set the level of a channel in Paradigm v4.2.0, but it isn't working. I've verified that all of the channel and space settings are correct on the trigger, and that all other settings to get Paradigm and Mosaic to talk to each other are also set correctly.
Explanation of Issue
On July 29, 2019 it was discovered that this is an issue in Paradigm v4.2.0. All other "Send Paradigm Action" types do work.
This issue was resolved in Paradigm 4.2.1, which was released for use on October 29, 2019. The alternative workaround is to put the Paradigm channel you're trying to control into a group, and instead use the Group Set Intensity type in your Mosaic trigger.