Fillet fails on specific edges for unknown reasons

[viernullvier]

Steps to reproduce

Note: This is still WIP, I've encountered this problem on two nontrivial models but haven't created a minimal example yet.

• Create a model with a couple of (curved) edges
• Add a new fillet group
• Use the edge picker to select one edge, a couple of edges, all edges

Expected behaviour

• Fillets should be applied to all edges (where it reasonably makes sense)

Actual behaviour

• When selecting a single "unproblematic" edge, the fillet gets applied correctly ✅
• When selecting multiple "unproblematic" edges, the fillet gets applied correctly as well ✅
• When selecting a single "problematic" edge, the fillet won't be applied with the error hint "Not done" ❌
• When selecting a single "problematic" edge in addition to other "unproblematic" edges, no fillets will be applied at all with the error hint "Not done" ❌

Example

Here's the first model in which I could reproduce the problem reliably. Each of the eight notches should have the same fillet applied, but one of them fails reliably.

Source document: oscoin.d3ddoc.json

Screenshot - the one on the bottom is the problematic one and has been left out:

Screenshot - with the problematic edge added:

[viernullvier]

Minor update on the document I uploaded above: It appears that the fillet will only fail if the offending notch is exactly aligned with the YZ plane. Displacing the polar array a tiny bit or rotating all notches to keep them from intersecting the planes will get rid of this issue, which makes it even weirder.