Motion lights outside fault

Sounds like defective sensors. Still under warranty? Most are cheap and not repairable.

Alternatively, is it really a problem? Sounds like they work, just flicker before going off. If they just flicker for a few seconds, does it matter? Could try removing the power to reset them, but they are probably on a switch and that's already been done.

V. interesting, since my front door light started doing the same thing about a week ago. After 2 years of working fine.

Mine is not on a timer, just a wall switch, a motion detector, and a ligth detector, and it has two possible On settings. One that it's on all the time and the other if it's dark out and someone comes near, it goes on. Usig the on/off switch in the right way determines which on setting it is, and this is complicated by another light where the instructions are opposite, so I can never remember which is which.

Power failures are rare, but even a short one can make it switch modes.

So now it flashes 3 times and then goes off. But sometimes being off is just a prequel to being on. Yesterday I went out and when I came back it was still off and didn't go on when I walked up the sidewalk.

Have to do some more testing.

Hmm. Your problems sounds trivial compared to mine. But it's still an interesting coincidence.

Could you cover one of the sensors just to see what would happen?

I would contact the manufacturer

As a test, try some good old-fashioned incandescent bulbs.

LED bulbs, in addition to making President Trump look slightly orange, often cause problems with dimmers and motion sensor devices.

CFL's can 'trigger' a false motion detection. The switch I use in my garden shed does this with a CFL in its field of view.

And as LeeD2019 wrote, LED's present an impedance too high for the motion detector circuit. I need to put at least a 40 W incandescent on my load or the LEDs flicker.

What's wrong, simply that they flicker before they turn off? So what, as long as they are ready to come on again when motion is again detected.

Yah, CFLs and LEDs for various reasons don't work well in some "smart" devices.

For example, I've got a garage door opener that wouldn't operate via the remote when the LED bulbs are lit.  Not a big deal, I just use swapped them for incandescents.