Dupes never work on hydrogen generators even if they are with a power control station. I'm not certain if this is the only generator that doesn't work with them (my guess if it isn't the only one it has something to do with the generators that don't normally show priority).
Notes: My dupes with the Tune up trait are set to the highest priority, and are working on my coal generators just fine in a power control room (set to priority 9 on them).
Steps to Reproduce
Build a hydrogen generator in a room with a power control station and wait for dupes to tune it up.
This issue has not been confirmed by a developer yet.