Oh no! I'll try to reproduce it and fix it. Do you know if it happened at the start of your turn, during your turn, or during someone else's turn? Did the mouse curor have the "waiting" wheel on it?
It was like turn 83, larger size of galaxy, one other race, Mutagenic/Casual. The save is still there I think. I *think* it was my turn, the cursor was normal and I clicked things - could see the reports - but couldn't bring up the planet build popups or give ships new orders, and End Turn was grayed out.
Please use this tool to download the saved game file and then send it my way: https://justaddlava.itch.io/vc-tool
My name is justaddlava on Discord, Gmail, and Reddit.