This results from the incorrectly formed url for Check-ins menu as: "/tkttimeline?name=<short_uuid>?y=ci"

To demonstrate the issue, try selecting Check-ins link in history of ticket 9195b1e5f3.

anonymous added on 2011-06-13 23:11:40 UTC:
Looks like this problem is not a priority in almost year.. So below is a work-around in case someone needs it: -- in the incorrect url for ticket history check-ins at the end change:

?y=ci

to be:

&y=ci

This will show the check-ins properly.

dmitry added on 2011-09-08 23:31:15 UTC:
I can't reproduce this -- has this been fixed?

dmitry added on 2011-09-10 21:05:48 UTC:
Fixed in [082c02a80c] (also ticket [53ed528478dbc42]).