I've experiencing this bug both with and without Enhanced Scouts mod enabled. In this report it's turned on.
It usually occurs on the first contact with a native settlement.
The game freezes and won't respond to any key press. Music keeps playing on background though.
At first I thought it could be the dialog card hiding some other dialog behind it, but it don't appear to be the case.

I'm unable to reproduce this bug using your savegame, and I can't find anything in the log file that could explain it either.
Perhaps there is a modal dialog hiding behind the large one? Have you tried clicking on the background of the dialog and tried moving it around?
You are saying the game freezes and won't respond to any key press ... but what about using the mouse? Can you select menus in the menubar, move dialogs (as explained above) or other things?
One thing that confuses many users is the "terrain selection mode" that you enter if you doubleclick a tile. The keyboard shortcuts for the units (like "Wait/next unit") are deactivated after entering this selection mode. You can go back by clicking on a unit, or opening a colony panel and closing it again. Perhaps this is the issue?
Yes, I've tried clicking around, move the dialog and click or access menu functionalities using alt + somekey. Nothing works. Indeed, it's a dialog hiding behind the first one.
Wha's strange is that it appear to happen only meeting the Tupis or any other native settlement using the Seasoned Scout. In this save, for example, I had met a lot of other settlements using another unit. Eveything fine until it became a Seasoned Scout.
This time, after a lot of stuff I was doing to post this reply, the dialog just behave correctly and showed up in front of the bigger one. The other times it occurred I have no luck and must close the game using the System Monitor, since it becomes unresponsive.
Last edit: Flávio Lopes 2023-05-20
The attachments
This issue is probably caused by overlapping modal windows. You might still be able to navigate using the TAB key and space bar.
We are currently working on updating all of FreeCol's dialogs, and this issue might be fixed as a part of that work (might be FreeCol 1.3.0 or later).