Cura: Support placement setting is blank and "settings updated" messege appears. Cura 3.4.1 - 3.5.1

[printingotb]

Application Version
3.4.1

Platform
Win7

Printer
At least on custom FDM printer

Steps to Reproduce
I am not sure when this happens, last time was when I discarded current changes from my profile. The changes had nothing to do with support settings.
It happens on different profiles and machines.

Actual Results
I get the message "Settings Updated" settings have been changed to match the current availability of extruders: [Support type]
And the support placement setting has become blank.
The star that indicates that there are changes to the profiles does not disappear when discarding changes and the support settings is still blank.

Expected results
My profile should remember the support placement setting and not suddenly loose the value.

Additional Information

Project file:
Support placement blank.zip

[Ghostkeeper]

I'm unable to reproduce this so far. Can you try with Cura 3.5.1? Maybe it's been fixed since you reported this.

I tried various combinations of discarding profiles, disabling extruders and switching materials to FABTotum Nylon (which has a different default value for Support Placement).

[printingotb]

I have been running 3.5.1 for a while. I am actually not sure if it is still an issue. I had it a few days ago but I could have been when I ran 3.4.1.
I'll keep my eyes open for a while and if it doesn't re-appear, we can close this.

[printingotb]

It's still here

If you open this project, do you get the issue as well?
Untitled.zip

I wonder if me running multiple instances of Cura at the same time can cause this?
Perhaps with me saving profile changes in one instance?

[printingotb]

Interestingly it says "buildplate" when viewed from the manage profiles menu.

I am quite sure it has been saying "0" when I have checked that before.

[Ghostkeeper]

If you open this project, do you get the issue as well?
Untitled.zip

This is a completely empty file. It was saved as normal 3MF instead of as Cura project. Or at least, it appears to be. The cura folder is missing from the 3MF's zip archive.

Interestingly it says "buildplate" when viewed from the manage profiles menu.

This is expected behaviour. If it said 0 then that might have been the bug.

[printingotb]

I must have made a mistake when saving that. The thing is that it shows up as blank in the settings in the main window but if entering the profiles menu it says buildplate.

I have had the issue a few more times but it seems really rare and not a big deal, I just need to choose a support setting and update the settings profile again.
Once 4.0 is out of beta I will make a clean install and merge all my old profiles from different Cura versions (I had to go back to 3.4.1 for Ironing and stupidly worked on some profiles in 3.5 and some in 3.4.1).

[JalteJKR]

I have the same problem, please watch my video https://youtu.be/vp-tibeVCjM

[printingotb]

I'm not alone :D
Nice video. I hadn't realized that the issue appeared every time I changed a support setting and then choose discard settings!
The issue goes away if I first update the profile with support placement to any of the options and then turn it off and update the profile again.

[JalteJKR]

Hmm, doesn't work for me :( I'm probably just going to copy the settings from my current profile to the default one that works :/

[Ghostkeeper]

Thanks for that video. It helped to deduce where this problem came from. I made a fix here: https://github.com/Ultimaker/Cura/pull/5795

I don't dare to make this change to master without letting it be reviewed by my colleagues so I'll discuss it tomorrow with them.