In the KSC screen the VAB and SPH are not selectable, other buildings are...

[rbreaker6000]

This is a bit tricky, it only seems to be happening after a seriously long session in the VAB and a disconnect reconnect. I'm trying to pin down the cause but it's sketchy, and because of long plays the log files are huge. Will update as soon as I can get a better debug

[rbreaker6000]

update: This is possibly just a KSP issue. Apparently my client crashed at some point and seemed to keep running :S

[rbreaker6000]

Guaranteed this is tied to quality settings. Got reference from 2 other players that it fixed it, confirmed myself. At max settings buildings are locked, on min settings they're open.
http://i.imgur.com/fttD6U5.jpg

[rbreaker6000]

ok, scratch that. It's simply when the first transition from syncing to ksc. If the mouse is over the KMP window it forces a lockout, same as the old VAB lockout ect. Can doop 100%

[EoD]

We have a similar problem on a vanilla kmp server when initially connecting to the game. It happens almost every time during the initial sync.
We had one or two occasion where it happened mid-game after a "Failed to launch vehicle due to incompatible parts" re-sync.

[EXC 14:13:58.372] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.373] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.374] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.375] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.376] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.376] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.377] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.385] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.388] NullReferenceException: Object reference not set to an instance of an object
[LOG 14:13:58.390] Clicked
[EXC 14:13:58.402] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.403] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.403] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.404] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.405] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.406] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.407] NullReferenceException: Object reference not set to an instance of an object
[EXC 14:13:58.408] NullReferenceException: Object reference not set to an instance of an object

The symptoms are:
You cannot enter VAB / SPH / Tracking Station
You can enter R&D but don't get out again.
You can enter Astronaut Complex and leave
You can click on both launch platforms, select design and kerbals but you cannot launch.
The Exit button (bottom right) does not work.

How to fix it:
Just disconnect and reconnect until it works. No need to change settings, restart the game or do other fancy things.

[rbreaker6000]

ok, so I can successfully dupe this when it works 100%, but other times it's hit and miss. All I can say is there's maybe a link to unity? or a situation while the game is being loaded? When I can dupe it it's as simple as the kmp window location, or orbiting to the top gimbal in sync, or the location of the cursor...
All I can do is put forth my general findings.
1: this bug seems to only occur on the initial transition from sync to KSC. I know of getting it mid-game, possibly after a sync though?
2: this bug also locks out the back button in KSC. Whether this is the same effect seen in the vab/sph lockup or due to something like a mouseposition conflict I have no idea.
3: when dupeable it's always involved a mouse position for me. Whether within the kmp window, or after scrolling the gimbal, ect. it's always duped consistently on a fairly accurate mouse position. This really confuses me and is the reason why I've assumed it was because the cursor was "over something" or "within a window". This frustrates me unendingly.

[Hounddog]

Just had this same issue about 10 times in a row... This is really a frutstrating issue... it takes me already like 5 minutes to synchronize and then you cant enter anything...

[bisam]

@EoD For me it is exactly the same.

We are using career mode btw, if that is any help.

But I found a nice workaround, as mentioned in the forum thread: I use SceneJumper http://kerbalspaceport.com/scenejumper/ With that it simply works, and after the first "SceneJump" the bug does not appear again.