Front disc coversion problems

Another way to localize the issue.

Wrap the rubber lines with a rag and vise grip them closed. Don't go crazy on the pressure you use to clamp it. I usually do the rear first. If the pedal gets solid when the line is clamped, the issue or at least one issue is in the rear lines, after the clamp. Can do the same deal with fronts.

Block off all 3 rubber lines and it's before the clamps if still mushy.

Yes crack the fittings right at the master and prop/distribution block when bleeding. One of the highest elevation points in the system is at your bends coming out of the master. Real easy to get air trapped in the bend. Make darn sure the line isn't going uphill out of the master before that turn down.