An OTH radar like JORN works properly when MUF (maximum usable frequency) is high, this almost during daylight, because you have good propagtion up 30 to 35 MHz during high solar flux in F2 layer, as in the last weeks. During nighttime the MUF goes down rapidly to 15 MHz atm, so have less range and resolution. The range of JORN is between 1000km and 3000km, this is limited to MUF and day- and nighttime. The same facts are for the Chinese OTH.....
So JORN may be on, but due to less range, caused by low MUF in nighttime, it couldn't catch MH370 at all. A good short overview of JORN is here:
https://www.airforce.gov.au/docs/JORN_FAQS.pdf
my 2 cent about OTH, Michael