TAD calling weird behaviour

[iagooteroc]

Hi. I'm doing TAD calling using Chromosome.find_tad on two samples that have 5kb resolution. At first I did the calling with add_experiment(..., resolution=5000), but that resulted in very small TADs. After that, I tried with resolution=40000 and the TADs look good (see figure below)

However, there are still two chromosomes that have very small TADs, chr13 for example:

I tried to re-run those chromosomes with 20k and 80k resolution to no avail, it still results in small TADs.
I'm running pytadbit v1.0.1 (pytadbit.version says v1.1 though) and this is my code:

from pytadbit.parsers.hic_parser import load_hic_data_from_bam
from pytadbit import Chromosome

hic_data = load_hic_data_from_bam(BAM_FILE, int(RESOLUTION), region=CHROMOSOME, ncpus=int(THREADS))
crm = Chromosome(CHROMOSOME)
crm.add_experiment('EXPERIMENT', hic_data=[hic_data.get_matrix(focus=CHROMOSOME)], resolution = int(RESOLUTION), ncpus = int(THREADS))
crm.find_tad([('EXPERIMENT')], n_cpus=int(THREADS), normalized=False) 
crm.get_experiment('EXPERIMENT').write_tad_borders(savedata='TAD_{0}_{1}.tsv'.format(CHROMOSOME, RESOLUTION))

Any insight would be appreciated, thank you.