You may have wetting agent stuck to the reels; wash them well in hot water.(posted 8894 days ago)I think you're simply getting airbells. Try this:
Load only one reel, put it on the bottom, then put the empty reel on top. Use only enough solution to cover the bottom reel. You _want_ that huge air space.
No prerinse, pour in the developer, bang the tank a couple of times, then invert continuously for 30 seconds, at the rate of at least one inversion every two seconds.
Thereafter, invert the tank twice in five seconds every 30 seconds.