Can not use Storm Wave anymore

I was using the skill normally, made some trades, entered a map and the skill was not working anymore. Checked stats, weapon type, everything was right. The skill appears as available in the skills section but is grayed out in the skills bar down right.
Link to video: https://streamable.com/joneej
Hope someone can help. Thanks

Problem was due to a weird interaction between the active weapon set and the skill, which does not change automatically on use as it does with other skills.