I'm having a visual glitch in this area, parts of the tileset are invisible
That is pretty weird. Which OS are you using?
64-bit Windows 10, Lenovo ThinkPad E480. I once had a similar glitch in Godot but it only happened in the editor. I remember reading that this game was made in Godot as well.
Dang... I cannot replicate this... I've never seen parts of the tilemap disappearing like that... I would get it if all the thing went away but just parts of it is beyond my understanding.
This could help, however it seems like it doesn't work always. Having this problem in the editor was very annoying (it hasn't happened after I updated Godot). Anyway, I've enjoyed this game a lot so far!