I had a similar issue and in the end I found a work around by creating a junction using the MLINK/J command. Your going to need to know the existing path to your MT4 data folder in C:
1) In windows explorer go to C:\Users\XYZ\AppData\Roaming and find your MT4 data folder
Move the data folder to your F:\ - Everything that was in C:\Users\XYZ\AppData\Roaming\MT4 Data Folder is now in V:\MT4 Data folder and C:\Users\XYZ\AppData\Roaming\MT4 data folder doesn't exist anymore.
2) Open a command prompt and MKLINK/J "C:\Users\XYZ\AppData\Roaming\MT4 data folder" "V:\MT4 data folder"
3)Make a new test file in "C:\Users\XYZ\AppData\Roaming\MT4 data folder". Do you see same file in "F:\MT4 data folder" ???
Delete the test file
If any program (even explorer) accesses C:\Users\XYZ\AppData\Roaming\MT4 data folder it is automatically redirected to F:\MT4 data folder
* just thought - Your MT4 data folder won't be called MT4 data folder - more like D9J9JSAHJSHDFHIUREIUR5U690 but I'll be damned if I'm typing that out 20 times!
This works for me on MT4 build 950 on Windows 10 but I basically ripped this solution from an unrelated problem someone else was having and thought it might work for my issue, so if you try it you're kind of doing off your own back, but I do hope it helps.
Now just got to try and get Tickstory working with build 950