I ran into the disappearing VAB menu bug as well. Drove me nuts these past few days trying to pin point what was causing it as I'm running heavily modded (just got a new computer and wanted to see what it could handle).
When I put in the .dll that is first suggested the bug goes away and I get the VAB menu icons back. But if I download and install the new V1.3 update then I lose the VAB menus again. I only didn't try the V1.4 because its a test version and I didn't want to risk running into something else wonky.
Here is the log file with the menu missing (using the V1.3 download)
No VAB Menu Buttons
Here is the log file with the specific .dll overwriting the V1.3 .dll Has VAB menu buttons
There is a very large difference in the two file sizes that i find strange. The only thing that I can think of that might have caused that is that when I did the first one I went into the alt-f12 menu and checked the dump log file box, but I immediately unchecked it. I didn't do that with the second one. I'm a bit new to this kind of stuff so apologize if I didn't do this right.
Oh, I'd taken out nearly all the 100+ mods I'd been using as well. The only mods in the GameData folder during these log generations are
000_Filter Extensions Config
Quick Mods (for exit and start)