Sidechain + 3rd party plugin issues

Have a strange issue which seems to happen randomly.
When activating a sidechain the audio seems to pass through to the plugin from the source track, but plugins don’t react to it.
If I solo the sidechain in the plugin I can hear the source, yet the plugin does nothing, happened with few different plugin companies (waves, fabfilter, wavesfactory)

Another issue happened with waves plugins in few projects - the audio doesnt go through them, they simply do nothing and nothing is shown in the meters

Anyone had these issues?