[Text not properly aligned between pages/baseline breaks]

I'm still very new to the world of DTP software, so do forgive me when I use wrong terminology and such.

As you can see on the screenshot below, which was taken from the bottom of the pages, something is not working the way it's supposed to. There's some sort of alignment issue. I made sure to tick the 'Align to Baseline Grid' box in the paragraph panel, but it still looks like this. It is copy-pasted from another document due to the way our workflow is set up, which doesn't feel like anything out of the ordinary, but even then... What am I missing? How can I make sure this does not happen?