For this film the agitation sequence may be too much: 10 seconds every 30 seconds gives hardly any stand time, i.e. the developer is almost in constant movement. If it works for other films you are happy with, then fine; this would also create more visible grain, which may be what you want - for less grain and perhaps less contrasty negatives a 'normal' agitation might be 30 seconds initially then 10 seconds every minute. To get back to the issue, I think I am correct in saying that this strong agitation could cause a 'wave' pattern that may lead to irregular development that this film emulsion may be sensitive to - there is a more scientific explanation that I have come across, but I think the basis is correct (now prepared to be doubted as I don't have the original article).
If you have developed this film before in the same way and not had problems, then, of course my suggestions fly out the window, so forgive my speculating.
Years ago I used to develop with the Paterson tanks (still do) using the rotary 'twizzle stick', method and occassionally with two or more reels stacked I would get one or more 35mm films with the development banding issue. This was caused by too vigorous agitation and a wave pattern through the sprocket holes - very regular uneven development, if you follow me - but I didn't come across it with 120 film. Since then I agitate by inversion and have never had any development issues: with inversion you must always have a good air gap as a full or nearly full tank will not displace the solution enough.
Forgive my long reply, I don't wish to imply that you don't know any of this, but, being a forum others may find it useful for the first time.
Regards, Mark Walker.
