Frame rate

Hope someone can help.

Have been asked to record a short sequence at 4k and 240 frames per second.

Have achieved this without any problems. If I load my frames into DJV and export as a Mov it runs slow and if I right click it shows as being only 24 frames a second.

If I render direct to an AVI out of Sequencer it plays at the correct speed of 240 frames per second.

Usually I always render to frames and load up in DJV, but cant get this to export at the correct frame rate.

Does anyone know if there is an option in DJV or an alternative software to exportin image sequence?

Thanks for any help, hope that makes sense!