Do the numbers still advance?
(I think those meters have a resolution of 0.01 kWh, so the least significant digit should advance after 10 flashes.)
Also in other threads, some have claimed that that LED flashes to indicate that the power is connected even when there is no load. That isn't how I recall that they worked, but there could be more than one sort of meter.
If you can actually see the numbers advancing when the switch is off, then I suggest that you take a video of it (just in case it fixes itself!) and report it to your supplier.
The numbers only go up per kWh unfortunately, so it is not practical to switch off the mains for long enough to find out
According to the manual, the LED should actually stay on all the time if there is no load. If it is still flashing then this should indicate that watts are still being used.
I will try to take a photo and a video.