LED Bulb Always Flickers Or Doesn't Turn On

As an alternative, you may want to consider installing GU10 bulbs. They are the same general size and shape as GU5.3 bulbs so many fixtures are compatible, but they operate on line voltage so there is no longer a need for the transformer. You would just need to remove the transformer and replace the socket, which is a very small cost on top of the bulbs. It is the best way to negate the flickering and troubleshooting headaches

My bathroom is fitted with six traditional 20W GU5.3 / MR16 bulbs, and I want to replace them with the smart home equivalent. The only one I could find with the same socket type is the 5W Osram Smart GU5.3 bulb.

I bought three of them (to start with), but when I put the bulb in, and flip the switch, the bulb either flickers erratically for a few seconds, or does not turn on at all. This doesn't look like deliberate behaviour.

All three bulbs do the same, they do it in each of the six sockets, and they do it even when all the other conventional bulbs have been removed. However, with an external power source, I was able to test the bulbs, and they all work perfectly, so they're not duds, either.

The bathroom has a regular switch, not a dimmer switch.

What could be causing this issue? How do I resolve it?