It should be possible to store the level before turning it off, and then set the DimLevel again, but if you do to, the dimmer turns on again….
I have sporadically experienced (mostly not!) the same thing with the fibaro dimmer 2 as well as the RoBBsmarrt zigbee dimmer.
When the light is turned on, sometimes it stays off because the dimmer is set to level 0. In the end I have solved this with every ‘on’ command, after 1 second setting the dim level to a certain fixed value.
Hope this helps.