Error when starting new or opening project in Mastodon

I’m trying to work with the Mastodon plug in, however after updating my Fiji recently I get an error as soon as I try to open a project or start a new one by choosing a saved .xml file in Mastodon (which wasn’t happening before).
I tried installing Fiji again and installing Mastodon again, but I still get the same errors.

When I try to select an .xml file it recognizes it and lists the timepoints and views, but then still gives me an error when I click ‘create’.

Could someone help?
I’m sure I’m making some simple mistake in the installation/update part, but I can’t figure it out.

Thank you!