[kronolith] 4.2.3 "Admin access not enabled." when editing calendars

[Jens Pranaitis]

Hello,

whenever I try to edit a calendar within kronolith I get a red popup 
stating "Admin access not enabled." and the page displays the loading 
gif. Adding/modifying individual dates works fine. I'm running

kronolith 4.2.3
horde 5.2.3
imp 6.2.6

All other packages are also up to date. I tried downgrading kronolith to 
4.2.2, but the problem persists. I think the problem cropped up some 
time in the past 2-3 weeks, but I'm not sure as editing owns calendar 
isn't an everyday action.

The POST request resulting in the error message is:

https://[SNIP]/horde/services/ajax.php/kronolith/chunkContent

with params:

chunck: calendar
token:"[SNIP]"

In the apache logs the request returns 200 without any further message.

Any pointers to what I could have misconfigured or how to further debug 
the issue would be really appreciated.

Kind regards,

Jens Pranaitis
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