Kicks sound disappearing in CE5

Recently I was working on a project using a hardcore kick VST. It sounded ok during playback but when I try to add another instrument the kick tracks sound is gone which is weird because the led on the track is ok and I hadn’t made any changes to the instrument. This has happened to me on several occasions using other kick VSTs suck as AM Kicklab and others. Anyone know what the problem might be?

probably “masking”.

What can I do to rectify the problem?