I found this line that uses very similar !(unpaved) type command but does NOT CAUSE an error on mkgmap compile.

highway=tertiary_link & !(mkgmap:unpaved=1) & bridge!=yes [0x08 road_class=1 road_speed=1 resolution 20 continue]

but I do have a complie error with :

(highway=residential | highway=living_street | highway=minor | highway=unclassified) & !(mkgmap:unpaved=1) & bridge!=yes [0x06 road_class=0 road_speed=2 resolution 22 continue]

The only difference I can see is 2 Parentheses back to back seems to cause a problem

Greg