Identified reactions using humann2_regroup_table

I’m a new humann2 user and I’m still trying to understand some of the humann2 output:

I created the files “p144C_pathabundance.tsv” and “p144C_genefamilies.tsv” (among other files) with the command

humann2 --threads 1 --input p144C.fastq --output humann2_out/

p144C_pathabundance.tsv (14.9 KB)
p144C_genefamilies.tsv (925.2 KB)

Then, I retrieved the reactions using the command:

humann2_regroup_table --input p144C_genefamilies.tsv --groups uniref50_rxn --output /outputFolder

And got the file “p144C_regroup_uniref50_rxn.tsv”.

p144C_regroup_uniref50_rxn.tsv (190.9 KB)

Some of the reactions in the regroup file are part of pathways listed in the file “p144C_pathabundance.tsv”. But the majority of the reactions belong to pathways not listed in the pathabundance file.
One example: The reaction GDPMANDEHYDRA-RXN is listed in file “p144C_regroup_uniref50_rxn.tsv”, but any of the pathways that have this reaction in it, are listed in the file “p144C_pathabundance.tsv”.

Here a few more reactions with this behavior:

Could you please help me to understand the reason for this behavior?
Thank you.