Custom scenario save format not working

[clumpyrct2player]

Hi everyone,

I posted about a month ago with an issue I am having with the new Open RCT2 save format. When I try to create a custom scenario it saves the file as .PARK.SC6.

I used to be able to change the file type to just .PARK myself and that seemed to fix it, but now it keeps refusing to save my progress. Weirdly, I can change the map size and it'll also save any changes I make to the landscape, but any objects I select such as rides will be unselected the next time Iaunch the file. My scenario files save as .PARK first time so these don't seem to be affected. I almost always play with custom scenarios and I'm desperate to make a new one, so it's made the game essentially unplayable for me

I really need some help and I don't understand what I'm doing wrong. I'd really appreciate any advice.