ECG only works intermittently...if at all

If you think your watch has an issue have Apple perform diagnostics on it. Do you have Apple Care?

In the US you can call 1-800-MY-APPLE.

Genius Bar Reservation and Apple

Support Options - Apple

Official Apple Support

Yes, wearing with wrong orientation inverts the wave and shows false information.

It does sound like a hardware issue. I’m not sure but I think Apple Retail Stores can diagnose the issue.

Genius Bar Reservation and Apple Support Options - Apple

No, OP seems more related to Digital Crown or individual physiology issue. I’ve seen hand cream and lotions interfere, which I assume acts as an insulator of sorts.

Jeff Donald wrote:

Yes, wearing with wrong orientation inverts the wave and shows false information.

As somebody that’s performed a whole lot of three lead and twelve lead ECGs, I’m curious about that.

Cardiac lead one as measured by Apple Watch goes from arm to arm across the heart, an electrical path which seemingly isn’t effected by the orientation of the Watch.

The waveform direction is based on current flow (electrical polarity) traveling toward or away from the Watch, which seemingly isn’t affected by the orientation.

Reaching the digital crown can be more awkward, certainly.

Buttons right and buttons left (without changing the orientation settings) both captured fine, and the waveform polarity is correct with both.

And even if Watch is detecting directionality across the watch back (which is not showing in tests), it still wouldn’t have this outcome.

And yes, this seems hardware-related.

Have you tried different fingers? I find I have to press with my finger fairly hard, but not so hard as to depress the Digital Crown.

My last thought on this, do you have your Watch oriented properly? In other words is the wrist setting and Digital Crown setting correct?

iPhone > Watch app > General > Watch Orientation > set correctly??

Bottom image oriented correctly (right wrist) and top image oriented left wrist.

Okay, arm selection. Not button orientation. That makes sense.

Sinus inversus is the natural version of that.

Still not going to cause the reported problem, though.