Some newly created Nodes aren't showing up in home assistant

Hi there,
being relatively new to Home Assistant, I’m still learning some of the rather basic things of HA. This is a hard nut to crack: some new temperature sensor nodes w/ ESPHome won’t show up. Most did under notifications where I could include them with one or two clicks. Great. Others simply won’t.

Other forum members suggested to wait a while, which I did, but it didn’t help. There also were remarks to make sure to have different names in .yaml, which I also did. I also double-checked whether they have proper wifi connection or not (they have, with a lease, I can ping them). So that didn’t help much.

How do I manage those hidden nodes? Where in the HA UI can I find them? If nowhere, how’s it possible to make them apear? Wipe a node and start from scratch didn’t help either.

I also have some WLED nodes on the network which integrate like a champ. Same here: most nodes show up in a couple of seconds, but one single one won’t. Not in a week. I checked every setting between similar nodes, all networking/syncing features are identical. Logically it should show up. But it won’t.

What’s going on here? Is HA picky in some regard? Is it buggy as hell? I don’t know, just guessing here.

Thanks for any help coming along.