That's normal, sometimes crafts 'gray out' and sometimes they disappear.
I wish it was more consistent..
The Wizard's Portals are very very good. They give 4 energy every 5 hours, but you can upgrade them with Golden Troll Tokens so they drop 8 energy every 5 hours. I believe it's another 90 Golden Troll Tokens to completely upgrade 1 Wizard's Portal to the max.
The Mythic Research Center is terrific, and you'll want it anyway, sooner or later. But it does not give you anything when you build it.
It's a place where you can build creatures, but they all cost Golden Troll Tokens (and other stuff) to craft.
You can craft daily and weekly energy droppers, and lots of other things. Check out this thread for more info :
https://forums.storm8.com/showthread...=1#post1366451
Both are great, there is no wrong choice.
I went with the MRC first and then crafted all the Unicorns and then Alicorns. But now I have 2 Wizard's Portal's I absolutely LOVE them.