Does freezing non-freezable liquids affect life span I've created my own sauce, bagged it and left in the freezer for many days. It is still not frozen stiff (details to follow). I'm struggling to know how to phrase this question but, I'm concerned that since it's not frozen stiff that it's life is therefore reduced. 

My freezer is to -18°C.

The ingredients are 300ml water, 100ml white wine vinegar, 2tsp tomato sauce, 2tsp plum sauce, 120g sugar and 2tsp corn flour. 

I've Googled freezing white wine vinegar and corn flour to see if these prevent freezing (due to the alcohol in the vinegar and it was just a guess to search for corn flour) but my searches provided no answers. 

So, my 2 questions are why does this mixture not freeze and does it affect the life it can remain in the freezer because it's not frozen or is the fact it's still in the very cold environment (-18°C) the thing which means it's safe for a month or two?
Most sauces do freeze solid, but it is the temperature, not the solidity, that matters for food safety.

The hardiest bacteria, temperature-wise, are psychrophiles and can grow in temperatures as low as -15° C. Since they can't grow in temperatures above 10° C, they are very rarely found in food, but if your freezer is actually at -18° C (and you've verified this with a thermometer) then the food is quite safe.

Practically speaking, most of the common foodborne bacteria are mesophiles (Salmonella, E.coli, etc.) and don't grow well below 20° C. It's impossible for any of these to grow at even a "warm" freezer temperature.

Bottom line: Check your freezer temperature (and, if you're really paranoid, the food) with a thermometer to make sure it's working properly, but otherwise, don't worry about it.

P.S. Vinegar lowers the freezing point slightly, but more importantly, sugar causes the other liquids to freeze into much smaller crystals, which may give the appearance of not really being frozen (think of "soft" ice cream). Plum sauce also tends to contain various gums such as xanthan gum as thickeners, which are also used to keep commercial ice cream soft.