try going to Preferences/settings (ini file)/P Drive/Path to your P Drive.

For me it works just fine, I am using the tools Dev branch though.

It could be antivirus too. I had a conflict before where game updater didnt work with my antivirus.

Hmm could be mcfee ill try it
All other buttons in the UI work and path to p in the ini is correct and manual operatiin of the mapdisk.bat is working ok on fail of the UI

Incidentally what is Dev tools ? Sounds like a strange thing to allow Stable dev engine and stable dev tool combos thats a possibility of nightmare or maybe I now see why its all fucked up lol

its the exact same thing as dev branch arma 3, but for tools. it's like a beta version. anyone can opt in via steam.

It isnt stable dev, it's just dev. there are no conflicts.

hmm you mean the Veta option that allows the BIG data files ?
i dont see any DEV tools options Just BEtA and i ve been on them all the time ,not sure its any different

anyway cheers for the help , it looks like MCFEE i just decided to leave it be and start it manually from the Tools folder myself , works ok

http://i.imgur.com/ZV3ZrT5.png

So strange I dont get that option , only big data files option

No matter I am happy with stable (ish)

Hello and thank you for your feedback.

Was this issue resolved?

Could you please attach files located in your Arma 3 tools folder in the folder logs? The files you are looking for are Arma3Tools.rpt and Mapdisk.rpt

Thank you for your feedback

Solved (ish)

The P:drive is created but only attributed to the User authority that steam was satrted with :

If you start steam as Admin : then P:drive is only visible to the Admin
you must then start as user manually by double click the mapdisk in tools folder to access it via the Windows UI.

Obviously because you have started steam as Admin then you can reach P:drive via the Steam tools UI and tools you start from there.

Disabling UAC on windows 8 so User has admin rights is not possible as Arma 3 is an App that suffers serious stutters if this is done.

Starting steam as user is also not an option because then tools do not work properly becuase the exe`s that are required during there use like only admin authority

Nightmare cant see a way past it other than persevere but thats Windows fault , fingers crosssed for 10 :)

P Drive has been reworked from scratch more than a year ago to bypass the UAC. If Arma 3 Tools is ran as a normal user, then, the drive P will be mounted for both, users and administrators.

Note: Regarding the drive P and how it works from the Arma 3 Tools Launcher, nothing has changed since almost a year.

That is not the case on win 8 pro x64 and never has been

  There is a complexity of  tools exe's starting viewers and second line exe's that simply allowing p drive to bypass UAC does not fix , pdrive as you know is only a subst , creating it does not then allow uac to be bypassed on the exe's contained within .

For example start steam as user then mount p , then start TB and launch bulldozer annd you will recieve viewer not found .
However if you start steam as admin then do the same all will be ok ,
however as a user you will not physically see the p: drive as a drive label because your a user not admin .therefore you have to go direct to the armawork folder or go via the open file in the tool UI.

I have started p drive via the bat as both user and admin since day 1 and still do if I do it through tools ui it will only show to the authority that started the steam exe .