The only other thing I can think of is if you used your magic wand to create the fill and how those settings are set up. If those settings are too high and you have the tracing method set to Linear Segments you may generate a fill like your first screenshot...but you would see this fill with it's segments.
It is interesting to hear you can actually snap to the intersections of the segments...this tells me the fill in the original profile has segments.
Maybe redraw the profile.
Robert J. Garand
ArchiCAD USA 27-Build 5001 USA FULL
Windows 10 Prof (64 bit) - Intel i9-10920X CPU 3.50 GHz - 128 GB RAM - NVIDIA Quadro RTX 5000