When you add a tag, link or anything else that opens a modal with suggestions and your cursor position is close to the top of the screen, the top of the modal drops off-screen.
Thanks for the report @karel3s1,
We’ve noticed this as well, it was a side-effect of fixing the coupler from overflowing in the pinned pane, since we’re attempting to place it within the bounds of a card. We will fix this in 3.1.2 as well 
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