I have always been processing my 8*10 film in a print drum and never had below problem.
Let me first give the details:
8*10 HP5+ exposed at 200 ASA, processed in PyrocatHD; either as 10:10:500ml (for 2 films) for 10 minutes for N and 15 minutes for N+1 (totally empirical found figures).
In a Jobo CPE2 at 22degC, slowest rotation setting. Using a 2850 print drum, which takes 2 films.
Below is one extreme example, in the sense that the light was very flat (snow and mist) , I used a N+1 here, and printed it on VC FB Grade 5:
And a more detailed look here (used Photoshop to exaggerate it):
As you can probably see there are some weird slightly higer density streaks in the sky, and a small band on both short sides which are stronger developed.
I realise that this an extreme case with this N=1 and grade 5 print, nevertheless I have seen the same thing (less strong) in N processed sheets under more normal light, on the other hand: from the same series are this and this one, which do not show said effect (although these examples are portrait orientation, that should not matter, they are perhaps more "busy" than a featureless sky).
I do not understand how this is happening, AFAIK this is not bromide drag, what you see when you have a deep shadow next to a strongly exposed sky and a almost exhausted developer.
I did switch from a 1:1:100 to a 2:2:100 dilution of PyrocatHD because the amount of active developer is (too) low at 1:1:100 it seems. Cannot see why that should cause these streaks.
Solutions could be:
Tray development: rather not please..
Buy a bigger Jobo and a 3000 series tank..space and money are the problem here..
I do have a Patterson Orbital, but only 1 sheet at the time, and not temperate control and that handy Jobo lift..
Maybe I should slightly tilt the print drum every minute or so, not so much that the developer flow out of the hose, but enough to mix "horizontally
Suggestions more than welcome,