Cura suddenly will not set model flat, does not have full tool list.

[bricoyle 0]

After 4 months of problem free use, Cura 4.8.0 changed. Now models  do not position flat. First image shows Z = 0, but model is ~3mm above plate.
 

 

When I press "lay flat" tool, model positioned at weird angle, not flat.

 

Also, this tab used to have 3 options (until last week).

Perhaps Cura had some changes? 

1. Can I roll back?

2. Should I reinstall?

3. Is there a configuration fix?

Thanks.

[gr5 2,225]

It's pretty easy to have multiple versions of cura.  At least for me.  As long as you don't create any profiles.  I don't create profiles - I use project files which in my opinion are much better.

 

Is it possible that your STL has a stray triangle "under" the part somewhere?  Or even just a line (triangle where all 3 points are colinear).

[bricoyle 0]

Screenshot of stl. Upside down to see better. No stray triangles.

[ahoeben 1,986]

The "3rd icon" (for the tool to select a face to lay flat on the buildplate) requires OpenGL 4.0. If your GPU/driver does not support OpenGL 4.0, or if you have configured Cura to use "compatibility" rendering (OpenGL 2.1), then that tool will not be available. Check the "Force layer view compatibility mode (restart required)" option in the General preferences.