Low-voltage lights turn on then start to flash
It is a common problem with Triacs on LV loads.  I am assuming you have a 12Vdc wall convertor on perhaps 1-2A for white LEDs.  The Triac conduction can fail to have the necessary holding current at low levels. The load is insufficient and nonlinear in that it does not present any load below 9V or a certain phase angle on the triac. The threshold is thermally sensitive so the Triac  triggers a flash then skips a few cycles until it cools which  then repeats like a porpoise or motor-boat bouncing in waves.  The thermal resistance and dynamic impedance of the triac with a small nonlinear load  causes these time constants and frequencies with the LED load. 

It is a complex stability problem from insufficient load on the Triac dimmer.  Adding one small normal bulb would fix that. Perhaps only 8W or 25W.

Better dimmer designs, can also prevent this with trailing edge phase control instead of leading edge or smart current sensing with better triggering.

EE since 1975.