Second update: after further RTFM it seems that blanking of the display occurs when "the supply is neither in the constant current or constant voltage mode. This happens when the output is foldback current limited or driven into overload by an external source.
Interesting. I have these blinking displays although there is only a DMM connected to them. The DMM displays the correct voltage (with less than 1% deviation). So no overcurrent and no external source...
TBC - cheers
Martin
Martin