We are looking into this as it is probably related to the recent bandwidth fixes.
Thanks for reporting the problem.

I've posted another update that adds a 'Reduce network bandwidth' option to the general options menu. The game should use less bandwidth overall than before, but checking this box will cause it to use even less, at the cost of less frequent updates of information.

Leaderboards should be up to date if the option is not checked.

I was keeping an eye on the score updates yesterday, watching my score for Puzzle 465 on both the current client running and on another client running a second instance of the same puzzle on a different track.
I was comparing them with the score shown as registered on the website.

I was running the latest version of the software - version ending dafd5
but I did not have the option to reduce the network bandwidth checked.

Actual Client1 LB Client2 LB Website
23.45 10534 10534 10530 10534
23.46 10535 10534 10530 10534
23.47 10535 10535 10534 10534
23.51 10536 10535 10534 10534
23.52 10537 10536 10534 10534
23.55 10539 10537 10534 10534
23.58 10540 10539 10534 10534
00.00 10541 19540 10540 10540

The "leaderboard" on the first client showed the same score as was given for the puzzle at top centre screen but lagged just a little bit behind all the time.
The score on the website was correct at 23.45 but did not update until 15 minutes later, missing out all the interviening scores
The score on the second client leaderboard updated just after the website.

We observed something similar at the end of puzzle 462 before the most recent update.

This lag is only really a problem at the end of puzzles where it becomes very relevant to have an accurate idea of your own and other peoples scores, particularly if the competition is close.
If someone makes a large jump in the 15min before a puzzle ends but the updates are such that it does not register - they are not going to be happy!

Not sure if this problem can be addressed without upsetting the bandwidth again

Scores should be updating more often if you don't check the reduce bandwidth option.