Partly removed data after denoising

Dear all,

I am working with CONN for a longer time now. Now I stumbled over a problem in my data which was preprocessed with CONN:

preproc_STEPS = {'functional_art' ...
'functional_center' ...
'functional_coregister_affine' ...
'functional_segment' ...
'structural_segment' ...
'functional_normalize_indirect' ...
'functional_smooth' ...
};

batch.Setup.voxelmask = 2;

batch.Setup.voxelmaskfile = subject_specific_brainmask_based_on_T1;

I then check the result, which is now added the prefixes of "sw" to my filename. The data range was change (before -15000:16000, now -900:900) which is fine, however some artifact appeared in my data now - see attached file, blue circled.

When applying denoising, see below, some party of the right lower brain get zero amplitude strength and this data is in that state unusable for my further analysis.

batch.Denoising.done = 1;
batch.Denoising.filter = [0.008 0.9];
batch.Denoising.confounds.names = {'CSF', 'White Matter', ...
'realignment', 'Effect of rest'};
batch.Denoising.detrending = 1;

Does anyone know what causes this artifact, or how to remove it at any stage of the processing ?!

Greetings and all the best,

Daniel