Anyone experienced this weird transfer problem?

Guess not then!

What happens if the transfer goes through?

If its just a glitch where the numbers are wrong then i wouldnt mind at all. Would be funny though if you spent that much money on a single player

Not sure what happens when the transfer goes through yet, i'll give it a go and see. I'll make sure i save it first though!

I think I have found out where the problem came from. Basically, I was getting the 'could not connect to steam network' message, constantly so i looked it up online.
I found this website where someone had solved the issue, so i tried it myself. http://www.ghacks.net/2012/04/19/fix-steam-error-could-not-connect-to-steam-network/

This is the procedure i followed and it did solve the problem of actually getting FM up and running.

Please exit Steam and go to the folder called C:\Program Files\Steam\ (this is the default location for a Steam installation – if you set a different installation directory, you will need to browse to it).

Delete all of the files in this folder except:

The \Steamapps\ folder and Steam.exe (this file is listed as an application and features the black and white Steam logo)

Restart your computer.

Then, launch Steam.exe from within the Steam installation folder, and not from a pre-existing shortcut.

With Steam running, re-test the original issue.

Now i'm thinking it can't be a coincidence?

It is because the game does not have implemented floor value for its calculations, so lot of times numbers go to negative values and impossible for RL but that is the result of calculations. I was interested about similar problem so I downloaded in game editor to se what are the values and e.g. there was a club (NK Osijek) that had two relegations in a row and when I looked the average attendance it was -2435 in editor(because it subtracted from allready low attendance). Same goes for transfer budget, you have running budget you can spend in entirety and if you have big costs in wages it will be negative very fast and if the game adds some value on that negative value. In your case it was calculating 10% wrong it got some negative number and it multiplied it (maybe you overpaid the player ) or it tries to get the 10% of -1$ (if the value is not set)