Hello!

This issue seems pretty old. However, there is still no general solution for this on the forum and, this may be the best place to put the answer. So, we faced the same problem and we found the following:

1. The problem is in the function read_group of the file 'calendar.py' in class 'calendar.event'. The developers intentionally added the code to make all groups empty, explaining it with the comment “remove the count, since the value is not consistent with the result of the search when expand the group”:

for groupname in groupby:

if result.get(groupname + "_count"):

del result[groupname + "_count"]

2. We have tried to remove the overwriting of the function and it works more or less OK. If to remove above stated 3 lines it would be also fine. The general conclusion is that if you really need grouping in calendar, you have to modify calendar.py file. There is certain risk, that there would be some other bugs, however we haven't revealed them after a week of exploiting.