Hi Charlie,
Thanks for your information. I can see an issue with the metronome taking a while to set up, which likely is related to the tempo changing when moving between songs taking too long. I've figured out how to improve this and it seems to rectify your issue.
For info, the metronome tempo usually only changes at the end of the last bar playing once it is ready, so if you have a song with a very slow tempo and change songs on beat 1, you will have to wait until after beat 4 before the new tempo starts (assuming you are in 4/4).
It sounds like you are enjoying the light theme. You can go back to a dark menu (and song display) from the "Settings > Display > Edit or change current theme" page if you want to check that. Both metronome colours should be a little more visible in light and dark themes.
The fix for the metronome will be in v6.5.8 and will be released this coming week (I try not to push updates between Friday and Sunday unless there is a major bug since this is when the app needs to be as stable as possible due to highest usage).
Thanks for you continued support in helping improve the app
Gareth