Note: This is NOT the rewards eggs. These three eggs are from critters that I found out in the wild, fed, petted and looked after until they were ready to drop an egg. Only it's not letting me transfer any companion eggs, regardless of the source.
Usually on expeditions, if I come across an interesting or cute critter that I want on my main save, I'll get an egg from it and, after the expedition has ended, pass the egg(s) to my spouse (we always play expeditions multiplayer together), reload into my main save and have him transfer back to me.
With this expedition and the new transfer mechanics, we were celebrating not having to do the giving each other stuff and reloading to transfer. Only, I can't transfer eggs that I got from creatures along the way. We started the expedition from our main saves (to see what that was like) rather than starting a new save like we used to.
We also tried the method of me passing the eggs to spouse, swapping to the main save and then spouse giving them back but that doesn't work because as soon as he tries to join my game, it starts the expedition for him again.
Is there any way I can transfer these? Or is my only recourse to back track through a heaps of systems to the planets I got these critters from and get the portal glyphs to then travel there after I've swapped back to my main save? :/
EDIT; I also just noticed I can't transfer the Memories either - I usually like to keep these sorts of things in storage containers as 'souvenirs' of expeditions :(
The game has a lot of strange limits like that. Like allowing only 10 Message Modules, where Minecraft worlds allow infinite signs (or at least such a high number that, when you search how many are allowed, you can't really find an answer). Or only allowing you to store 16 Personal Wonders, even though they're just stored seed values, which are also about as simple as storing a text string.