Just updated to 5.13. I hadn't used TF in about 8 months (the only reason I boot my Windows VM), so I have also downloaded a ton of updates to Windows 7. Anyway, it was working fine in April. ;-)
Tiles that aren't loaded just keep the "downloading" tile forever. Nothing ever seems to time out, internet downloading is not disabled, etc. And if I look at the map files, nothing is getting updated (see below). Note that it's currently Jan 15. The timestamps from Jan 14 are, I'm pretty sure, from when I tried to expire the OSM tileset hoping that would fix it.
I have also tried moving all the .dat files out of the way, and while TF will create new ones, still no tiles.
Matthews-Mac-mini:~/Documents/My TopoFusion Files% ls -latr *.dat
-rw-r--r-- 1 mml staff 655376675 May 23 2013 Maps0.dat
-rw-r--r-- 1 mml staff 655374007 May 31 2013 Maps1.dat
-rw-r--r-- 1 mml staff 655375985 Jun 3 2013 Maps2.dat
-rw-r--r-- 1 mml staff 655360103 May 14 2014 Maps3.dat
-rw-r--r-- 1 mml staff 655411079 May 15 2014 Maps4.dat
-rw-r--r-- 1 mml staff 655471308 May 18 2014 Maps5.dat
-rw-r--r-- 1 mml staff 655384998 May 18 2014 Maps6.dat
-rw-r--r-- 1 mml staff 655385020 May 19 2014 Maps7.dat
-rw-r--r-- 1 mml staff 655376482 Jun 14 2014 Maps8.dat
-rw-r--r-- 1 mml staff 655371645 Nov 22 2014 Maps9.dat
-rw-r--r-- 1 mml staff 655371508 Apr 10 2015 Maps10.dat
-rw-r--r-- 1 mml staff 655363433 Apr 13 2015 Maps11.dat
-rw-r--r-- 1 mml staff 225342211 Jan 14 20:28 Maps12.dat
-rw-r--r-- 1 mml staff 6392295 Jan 14 21:00 MapIndex.dat