Very simple issue: Split with Lines does not appear to be working for me in QGIS 3.24.
My line and polygon are in the same CRS, you can see that they completely intersect. But but when I get the results, the polygon is unspiltunsplit (the layer has a single polygon). Very confused.
A similar post at Split with lines not fully working using QGIS suggests dissolving, but this does not work.