I am having the same problem - I cannot control the UCX in standalone mode with my MIDI fader device. It's not "clear from the manual that CC102 and similar are online (software) functions, not available in stand-alone mode."
On the contrary, the UCX manual states in section 28.5, on page 85, "The first row in TotalMix is addressed by MIDI channels 1 up to 4" and "16 Controller numbers are used: 102 up to 117 (= hex 66 to 75)... 16 Controllers (=
faders)..." and then in section 28.6, on page 86, "Still many functions, and especially the most important functions to control the Fireface UCX, are implemented in hardware, thus available also in stand-alone mode: All faders and pans of the first and third row".
Thus, if the first row is available in stand-alone mode, and the first row is addressed by MIDI channel 1, and the Controller number 102 is for fader #1, all of which works when the UCX is connected to the computer, then after I issue the command Options > Store Current State into Device (which presumably is the updated version of "Flash current mixer state" which is in the manual on page 87), and once I disconnect from the computer and switch the UCX to stand-alone mode on the device itself (from 'FA' to 'CC'), then finally I should be able to continue using Channel 1, CC102 like danielflores mentions.
Please clarify this point, and furthermore, RME should really publish a MIDI CC implementation chart for all Fireface models that have standalone mode.