Hi - just happened to see this. I think it's a combination of things.
First, IJ doesn't have the following that DW or LJ have, so many people probably don't even know about it.
Second, the last battle ran essentially concurrently with another similar one that WAS on DW and LJ. Staggering the fests and maybe a move to a more popular journal (or even an archive somewhere like AO3 might help.
Third, at least 90 percent of the prompts were for fandoms I don't know at all - which no only rules out writing them, but pretty much rules out reading the stories as well. I assume others have the same problem. Perhaps require prompters to prompt at least 10 different fandoms, so there's more variety?
I hate to see the fest disappear - but maybe it needs a little tweaking?