Whenever encountered you may have to look to some sort of a temporary workaround maybe coming from a third (3rd) party software.  One is accessible via your user account.  It is where you as a PIANOTEQ registered user can get Gig Performer at a discounted price.  And, it is also available as a demo.  That allows patch changes.

But to tell whether or not you need it now, you may firstly want to review a thread showing someone else had encountered a problem similar to yours: Pianoteq in Reaper with FCB1010.

Now certainly, if when you right-click on the sustain pedal you see in fact Sustain Pedal selected and are testing one of the default presets —without an italicized preset name showing— you have a high probability of the problem caused outside PIANOTEQ, otherwise DAW related.  Which is likely your case unless you get of course Controller 64 MIDI Events appearing inside the MIDI messages window (that is) under Options and MIDI.  (Beforehand you may need to verify if the connected keyboard even is sending at all Controller 64 MIDI Events verifiable via the PIANOTEQ window inside the stand alone copy.)

I'm pretty sure my DAW isn't filtering out any data, because the pedal works with other versions of PianoTeq. I contacted the maker of the DAW (MultiTrack Studio), and his response was this:

"IIRC the plugin has a setting for sustain. MultitrackStudioStudio simple sends the sustain controllers to the plugin."

...and the pedal calibration doesn't work because it isn't receiving any data from the pedal.

Have you selected Any as your Notes Channel?  If you already have, you may need now to refer to your DAW documentation or contact its support.

Anytime Global MIDI Mapping shows the word unsaved in parentheses, the setting has been somehow altered.

I have PianoTeq 5 and just downloaded PianoTeq 6. When I use them as standalone instruments, they both work fine. When I use them as VST instruments in MultiTrack Studio, the sustain pedal works fine in 5, but 6 doesn't receive any MIDI messages from the pedal at all. I dimly remember when I first downloaded 5 I had to do something to get the pedal to work correctly, but I can't remember what it was or indeed if the problem was the same. Any ideas? All the settings are the same in the Options window, and the pedal calibration doesn't work because it isn't receiving any data from the pedal.

If the MIDI tab in the options menu does not show any cc64 maybe your daw is filtering the cc data.