Something odd with DLC engines

[Cavscout74]

I had something strange happen this morning.  I was rebuilding an old probe design to send to Dres & wanted to see how some of the new engines stacked up against the original design - specifically the wolfhound.  But I couldn't find it in the engine tab of the VAB.  So I tried the search, also didn't find it.  Then tried the skiff & same thing.  But I did see the new vernier & the mastodon.  So I went back to R&D to double check that I didn't miss a tech node - the entire tree is unlocked in my career except one node at the end from a mod.  And of course nothing was missed.  So I went back to the VAB & there it was right on the engine tab like it was supposed to be.  Anybody else run into this or was it just some random oddness?   Maybe the game knew I was trying to go to Dres & was trying to prevent it.