Odd behavior when printing a certain wall

[Xeddog 5]

I have been using 4.11 for a while with good results.  But the last few days there is ONE piece that doesn't print correctly.  It is a trapezoidal shape and there are two sides that do not print as straight.  In the picture, you can see where there are gaps formed when the nozzle moves outward at several points.  There is another piece that this one mates to, and has the exact same dimensions, but it does not have this issue.  I have tried turning it over, and also rotation it around the Z axis in several positions, and nothing helps.  I also used two different printers.  As a test, I sliced it using PrusaSlicer, and it printed fine without the gaps.
The piece was modeled with Fusion 360 (stl file attached), and it shows the entire side of the piece as one continuous face. 

E5+ Filament Guide and Runout Sensor - Post Cover.stl

[Xeddog 5]

Quick addition  - Cura 4.12 beta does this too.

[esopalumpa 3]

Cura has a tendency to generate a gap between the most-inner wall and the other walls if there are more then two perimeters. I don’t know the cause, but it’s a know problem for a long time.

Possibly a problem with the order of printing perimeters or calculation of perimeter-positions…

 

P.S. From the top if often looks like the gap is between the second most inner wall and the rest, but what looks like the most inner wall actually is not a wall, but belongs to the infill (parameter: Extra Skin Wall Count = 1 by default).

Edited November 7 by esopalumpa

[Xeddog 5]

Yeah, I know all about that gap and it can be quite irritating.  But in this case, the gap is caused by the print head zigzagging the perimeter instead of printing a straight line.  It moves outward what looks like a line width every 25mm along the 95mm lengths instead of printing it as a single straight line.

And just for laughs that I probably shouldn't mention here, I had about 5 pieces laid out including this one.  I made all of my settings, sliced, and had an estimated print time of about 6 hours.  When I increased the print speed from 60 to 80mm/s (no other changes at al), the estimated print time INCREASED to over 1 day 8 hours.  🙂