I'm the friend running into the same issue, same game version (PC/STEAM v1.0.05.0549-S10) In the save game in the included ZIP, I was cancelling and then re-enacting 'Professional Soldiers' over and over until running out of influence, then re-loading the save after confirming that the event was progressing in my 'Events' section of the main menus. I was at 40/50 for Civil Evolution when I loaded the game again, was able to cancel and enact 'Professional Soldiers' again as normal for 510 Influence. After cancelling again, the cost to Enact the civic again suddenly dropped. At that point I exited the game and confirmed that my even progression was stuck at 41/50. I also attempted reloading the game a couple more times and confirmed the issue was persisting, and progression for the event is still sticking at 41/50. 

Game file and diagnostics attached.

Civics Overflow bug.zip

For me Necropolis is bugged (befor I completed the last achievment it was completed).

I also have this problem. I'm stuck at 46.

The same problem for me (PC/STEAM v1.0.05.0549-S10) .
I have 48/50 for the Civil evolution challenge. I have started more than 5 new games but the 48/50 Civil evolution still stay.
While starting new games the problem can not be in a specific game. It maybe appears with the new update version (PC/STEAM v1.0.05.0549-S10)

I'm also stuck at 41/50.

After updating last night I also can't progress past 40/50 Civics enacted. The first game I started after the update I got to turn 200 and not a single Civic was available. Since then I played 2 more games to competition and still no progress. Currently on patch [1.0.5.549] with no mods installed. 

I've stalled at 28/50 civics... I am such an underacheiver...

I'm Stuck at 27.

I didnt do the re-enact thing though so it is probably caused by the stacking cost reduction

As another commenter said, I had a few games where no civics appeared (after completing the other two event challenges) and while my civic count had steadily gone up previously it is now stuck at 47/50. I had issues in the 1st chapter with the feasts challenge and until yesterday the necropolis challenge wouldn't complete when I tried sacrificing pop on wonders (both as the maya and aztecs). Finally managed to get through that but it is getting really tiring to have such a buggy event.

many bugs that interfere with play. I'm disappointed

Same fun I have as others: 24/50. Oh, how I love to wait for patches and critical bug fixes during time-limit events! Such joy - best hobby ever.

Stuck at 33/50 since the patch, multiple games started. :(

The same here, after patch I stuck at 26/50. 

im stuck at 28/50

stuck at 48/50

I am also stuck on this. My progress stopped at 38/50

Same here. Stuck at 46/50 after multiple new games.