Cura: [3.5.0] Supports are generated beneath the model under the "real" support structure

[printingotb]

Application Version
3.5.0

Printer
Custom FDM

Steps to Reproduce
See attached project and pictures

Actual Results
Supports are generated beneath the model under the "real" support structure

Expected results
Same file and settings did not do this in 3.4.1

Additional Information
Cura 3.5.0:

Cura 3.4.1:

supportbug.zip

[diegopradogesto]

This seems to be a bug. The support is being generated from the top part and dropping down till the BP. I even tried to put a support blocker in the bottom part and the support is generated anyway.

[gravesfamily]

Just to add on, I'm seeing the same thing in a different model that sliced fine in 3.4.1, and because of it, I cannot actually print the item I need because the support inside the tunnel fills it up, making the tunnel useless. :-)

Using this object: https://www.thingiverse.com/thing:2783459

The tunnel in the object ends up with a support in 3.5:

While 3.4.1 does NOT have the same support generated:

Note that there is actual model above the tunnel that will have support on top of it as necessary.

[diegopradogesto]

Devs. CURA-5833

[b14ckyy]

Confirmed. Recognized yesterday on my first slice on 3.5.1 too.

If Printbed only, cura will generate printbed support for overhangs, even if parts of the model are underneath:

The big overhang on the back is ignored, this has a 45° angle.

if support activated anywhere it looks like this:

if support blocker is used in the top part, the support beneath will disappear on that line:

[dragoon88]

This bug has continued into version 3.6. It does not matter if there is support blocker on a lower overhang, or if the lower overhang is at a printable angle. The lower overhang angle in this picture is 33°. The other lower overhang has a support blocker.

[Ghostkeeper]

It doesn't reproduce in Cura 4.0 any more:

This same model did exhibit the bug in 3.6.

[Ghostkeeper]

Ah, yes, it looks like our internal ticket (CURA-5833) was already marked by our QA as fixed.