You're right! After changing the file extension the log was there. Please see the attached...
********* FSUIPC4, Version 4.949 by Pete Dowson *********
User Name=""
User Addr=""
FSUIPC4 not user registered
WIDEFS7 not user registered, or expired
306922 System time = 14/01/2016 08:55:01, Simulator time = 08:53:06 (16:53Z)
306922 FLT path = "C:\Users\Rick\Documents\Flight Simulator X Files\"
[Continuation log requested by user]
Running inside FSX on Windows 8.0
... FSX has been renamed as "$RF75N1V"
Module base=5E780000
318562 Weather Mode now = Theme
318562 C:\Users\Rick\AppData\Roaming\Microsoft\FSX\Previous flight.FLT
326312 System time = 14/01/2016 08:55:21, Simulator time = 08:50:02 (16:50Z)
326312 *** FSUIPC log file being closed
Minimum frame rate was 18.4 fps, Maximum was 20.0 fps
Minimum available memory recorded was 896Mb
Average frame rate for running time of 189 secs = 19.7 fps
Memory managed: 93 Allocs, 93 Freed
********* FSUIPC Log file closed ***********