Grommunio Web won't switch to any other tab than Mail

Hi,
I've recently installed the Grommunio appliance to move away from my very ancient Zarafa install (i know).
So far it has been working quite well, did some fiddling with rewriting to send as my own email address and such, great success.
To migrate the data, I used Outlook to export my whole Zarafa mailbox to a PST file, and then used outlook connected to the new Grommunio user again to import the PST into the freshly created user.
All seemed to go very well, however, now I cannot really use the web for anything other than email. When I try to switch to the calendar, contacts, tasks or notes, it just doesn't really switch, it seems to display the tab, but no other content is shown.
My mobile phone works well, as does Outlook. So it's not to big of an issue, however a bit annoying.
So far as I can see, in the firefox debug console, I see some javascript errors:

Uncaught RangeError: invalid language tag: ".UTF-8"
compareRecordProp grommunio-debug.js:72972
hierarchySort grommunio-debug.js:72889
createDelegate ext-base-all.js:21
sort ext-base-all.js:41
sort ext-base-all.js:41
doSort extjs-mod-debug.js:4493
fire ext-base-all.js:41
fireEvent ext-base-all.js:41
proxyNodeEvent ext-base-all.js:41
and:
Uncaught TypeError: Ext.fly(...) is null
select extjs-mod-debug.js:4433
selectFolderInTree grommunio-debug.js:72515
onHierarchyLoaderLoad grommunio-debug.js:122375
fire ext-base-all.js:41
fireEvent ext-base-all.js:41
handleResponse ext-base-all.js:41
processDirectResponse ext-base-all.js:41
createDelegate ext-base-all.js:21
directFn grommunio-debug.js:69532
and:
Uncaught TypeError: Ext.fly(...) is null
select extjs-mod-debug.js:4433
selectFolderInTree grommunio-debug.js:72515
onHierarchyLoaderLoad grommunio-debug.js:122375
fire ext-base-all.js:41
fireEvent ext-base-all.js:41
handleResponse ext-base-all.js:41
processDirectResponse ext-base-all.js:41
createDelegate ext-base-all.js:21
directFn grommunio-debug.js:69532
createDelegate ext-base-all.js:21
setTimeout handler*defer ext-base-all.js:21
directFn grommunio-debug.js:69533
createDelegate ext-base-all.js:21
requestData ext-base-all.js:41
load ext-base-all.js:41
expand ext-base-all.js:41
render ext-base-all.js:41
renderChildren ext-base-all.js:41
expand ext-base-all.js:41
expand ext-base-all.js:41
loadComplete ext-base-all.js:41
createDelegate ext-base-all.js:21
runCallback ext-base-all.js:41
processResponse ext-base-all.js:41
handleResponse ext-base-all.js:41
processDirectResponse ext-base-all.js:41
createDelegate ext-base-all.js:21

Does anyone here have any idea how I can resolve this? I'm thinking it may be an issue with the imported data from the PST file through Outlook, however I'm quite new to Grommunio so I'd like some pointers as to where I can debug this?
I did test by creating a new user without importing anything, there the web seems to work just fine.

Thanks in advance!