Just in case this is helpful to anyone else...
Thank you Gang! Your advice to switch the order of my continuous and categorical variable in the gltcode worked, so that categorical was first and continuous was second, like this. The program was crashing when the continuous variable (Negurg_mc) was first and categorical variable (Task) was second.

-num_glt 9 \
-gltLabel 1 'rsFC' -gltCode 1 'Task : 1*rest' \
-gltLabel 2 'Negurg_mc' -gltCode 2 'Negurg_mc : ' \
-gltLabel 3 'Negurg_mc_rsFC' -gltCode 3 'Task : 1*rest Negurg_mc : ' \
-gltLabel 4 'efnback_vs_rest' -gltCode 4 'Task : 0.5*efnback1 +0.5*efnback2 -1*rest' \
-gltLabel 5 'dynface_vs_rest' -gltCode 5 'Task : 1*dynface -1*rest' \
-gltLabel 6 'reward_vs_rest' -gltCode 6 'Task : 0.5*reward1 +0.5*reward2 -1*rest' \
-gltLabel 7 'Negurg_mc-efnback_vs_rest' -gltCode 7 'Task : 0.5*efnback1 +0.5*efnback2 -1*rest Negurg_mc : ' \
-gltLabel 8 'Negurg_mc-dynface_vs_rest' -gltCode 8 'Task : 1*dynface -1*rest Negurg_mc : ' \
-gltLabel 9 'Negurg_mc-reward_vs_rest' -gltCode 9 'Task : 0.5*reward1 +0.5*reward2 -1*rest Negurg_mc : ' \