Retaining voxels with signal dropout- fsl first level analysis after fmriprep preprocessing


I would like to ask a question regarding retaining voxels with signal dropouts. Specifically:

-I did all the preprocessing in fmriprep. Then, in the fsl first-level analysis, I cancelled all the preprocessing features except for the highpass filter, smoothing, and registration (linear, normal search with 6DOF)

-For most of the subjects, the fmriprep preproc_BOLD files have voxels with very low signal, mainly in ventral frontal areas - what we often call signal dropout.

-The output cope files don’t include any data from these voxels (i.e., their value is 0.0). I want to keep them in, so that they will be included in the higher-level analysis.

-I don’t have fieldmaps. Also, I was offered to change the brain mask of the fmriprep files or resample the anatomical data to them again, but I don’t understand how it can help since the fmriprep files do include these voxels and fsl does get them as input.

Thus, my question: Is there any way to keep these voxels’ data in the cope files?

Thank you very much