I had already written Dogmeat off as a lost companion having spent time last weekend fast travelling between every unlocked settlement trying to find him. Yesterday, I set out on a similar mission trying to find Curie who disappeared right after her companion quest activated. I started at the place where she's first found before going around the map searching high and low in every single settlement.

Now, the good news is that I found DogMeat. For some reason he went to Taffington Boat House (I let out an embarrassing squeal of delight when I saw him bounding towards me!). But, still no Curie.

Has anyone else experienced her loss?

I find a pedantic approach to companion location works.

Whenever I dismiss a companion, I'll go to their sent location to make sure they made it.

Ideally, I'll take the companion back to home base and dismiss them there, before picking up a new companion.

There are some plot points that make this tricky, but on the whole it's possible.

I had lost piper for a while. I hadnt dismissed her but no matter where I was she was nowhere to be found. Then I was heading to the abandoned shack in the glowing sea to get the x-01 PA and she showed up out of nowhere with about 10 bloodbugs chasing her...it was quite the entrance lol

The fact that they literally have to walk to whatever location you dismiss them too is stupid because they can run into trouble in between those locations. Codsworth took forever just to move between sanctuary and red rocket because I wanted my robot butler at my mansion overlooking my servants at sanctuary.

I once told her to head to Sanctuary but she never showed, so I went back to Vault 81 and she was standing by the medical center. Had her follow me to Sanctuary and dismissed her there, she stayed.

The weird thing for me is that I dismissed Curie to the Drive-In while I was at the Drive-In. I wanted to see if there was any witty-banter between her and Codsworth, but then the Settlement was attacked by Raiders, then she just vanished!

By the main Medical Centre in the vault or by the part where you find her? I didn't think to check the entire vault, just assumed that she could wander back to where she was found!

I found her by Doctor Forsythe's medical centre, not the hidden mole rat testing area.

Sadly they will get bogged down fighting attackers sometimes.
Even if the bad guys never notice you.

I had both Curie and Dogmeat missing. I ran all over the place and they were nowhere to be found.... so I had to use this

Dogmeat 0001D162
Piper 00002f1f
Cait 00079305
Strong 0003f2bb
Gravey 0001a4d7
Codsworth 0001ca7d
Valenine 0002f25
Deacon 00050976
Curie 00102249
Hancock 00022615
Danse 0005de4d

an example
pird 0001D162
moveto player
or
player.moveto

This makes the companion you want spawn at your feet. BUT don't summon a companion you havn't met yet. That can corrupt your save.