The same thing just happened to me. I was almost into Phycaon when a party of Lake Rats left the town and engaged. I was able to persuade them to join the Western Empire, but now they won't stop talking to me. I can click on Phycaon, or elsewhere on the landscape; it just goes right back to them and I can't escape. I also have a save file if Grim_Fandango's doesn't work.
I doubt my specs are needed too, but here they are just in case:
Version: 1.4.2.236056
Installed community-made modifications: None
Computer Specs:
OS: Windows 10 Home
GPU: Zotac Gaming NVidia RTX 2060
CPU: Intel i5-8600K
RAM: 16 (2 x 8GB) DDR4 G.SKILL Ripjaws V Series
Motherboard: GIGABYTE H370
Storage Device (HDD/SSD): WD Black 512GB Performance SSD - M.2 2280 PCIe NVMe
