I've been happily using Tixati for a while now, but since a few days ago any new torrents will indefinitely be stuck on 'Scanning 0%'. I understand this has to do with hard disk allocation, so I'm hoping it's not a hardware problem. Google reveals nothing though. Any ideas as to what might be causing this?

Wow, I found what was causing the problem. I had ticked the 'Incomplete file name format' box under Tixati settings > Transfers > Files. Is that option broken? Or should the default 'incomplete.$file' be replaced by something different?

Scanning 0% should be a "STATUS" you can sort by. Each transfer which has per-transfer options would therefore be pending with whatever lagtime the currently running causes.
Imagine trying to split your water pipe into three junctions, if you're upstream you notice no lag. If you're at any of the junctions and something happens there is a LAG. Imagine that for your computer bus speed, lagged by RAM and hard drives.

I would suggest doing the final-request rename option for EACH file, and doing per-category folders which move off you MAIN drive (not just partition like C: D: etc)... Physically different drives allow you to do parallel processing for data.
Open Task Manager (Ctrl-Alt-Del, or right click your taskbar check 'Task Manager') click down to your disk drives (usually C: is on disk 0). As you're doing certain things notice your reponse time in ms, 1000 is 1sec ... and active % time.

I would suggest trying to figure out the bottleneck for processing. In my case for my production system its RAM, of which Tixati uses alot more than other clients, but I feel its worth it due to the configuration options and the extra features (now with forum, YAY!)
Others with external/network hard drive shares could be an issue. Also basic multi tasking... It depends on how much information you want to glean from your own situation before trying to suggest changes. KH and the dev team have put alot of effort into giving us the best program for the best price.

What OS and version of Tixati are you using?

for the torrents where this happened:

were there many files?
were they large files?
were they large torrents?

on linux the incomplete flag works as expected and i have no stuck on scanning issues.

Posting here just to say that I've received the same issue of having all my new torrents stuck at "scanning 0%", and only got kick-started after unchecking the "incomplete file format". Checking it back still works after that.

The same issue appears for me, but new torrents scanning stuck not at 0% but at some random percent, 'Scanning 87%' for example. Unchecking Incomplete file name format fixes issue immediately. I'm on Fedora Workstation 31.

This option gives me same problem, but only with HUGE torrents (~280Gb / 140 files ) when I try to update old torent with new (few new files and one or two modified). Same thing — stuck at «Scanning…» Windows 10 x64 / Tixati 64bit. It's an OLD bug, first time i've got it was 5-6 years ago.