'using mi LTI provider as a HUB' ... like a true Moodle 2 HUB?
I've noticed this ... LTI link from Moodle A to Moodle B. Am the Administrator of both Moodles. If I've been tinkering with the LTI External link tool on Moodle A, and then see I'd like to change something on Moodle B (the LTI provider), browser has gotten cookies or something that affects my direct interaction with Moodle B in a new browser window. Only way to do that is logout, clear browser cache if using same browser OR use a different browser.
Haven't tried to combine the HUB I run with courses that also have LTI Provider. So you may have stumbled upon a combo that conflicts but maybe only for admin users who might be into both systems using the same browser.
'spirit of sharing', Ken