I agree with the consensus. Chemistry did not evenly contact the film. Refix and rewash.

Watch your agitation and make sure the reels are clean and dry.

I often use a toothbrush and hot water to clean mine out. Some people recommend putting them into the dishwasher. (Top rack with no drying heat!)

Inspect the reels to ensure that they are clean, dry and undamaged before using again.

This reminds me it's probably time for me to do the same!