Error with voxel thresholding in fsl's randomise

Hi,

Hoping someone here might have some experience running fsl’s randomise with the -x flag for voxel thresholding. I can run using -T for tfce just fine with no errors…however when I try to run with -x I end up with only raw T statistic maps. The error I’m given isn’t super helpful - “ERROR: program failed, unknown exception” and it happens right after the last permutation (5000th). Any ideas?

Thanks!

Best,
Kylie