I have a Flashair and I try to run a Lua script every time a new file is added to the card.
I set the LUA_SD_EVENT on the CONFIG, but when I add a file to the SD card nothing happens. Basically, I have the Flashair on my PC and manually add a file to it.
The LUA_RUN_SCRIPT on boot works properly.
I have found that running two LUA scripts on the flashair at the same time takes too much memory.
By that conclusion you should check and make sure that there is no boot-activated lua script with a loop running.
I have successfully added a "file-monitor" to the boot-script and then being able to replicate nearly the same functionality of the LUA_SD_EVENT.