WARNING: MetaPhlAn did not detect any microbial taxa in the sample

DESCRIPTION
MetaPhlAn version 4.1.1 (11 Mar 2024):
METAgenomic PHyLogenetic ANalysis for metagenomic taxonomic profiling.

info:
WARNING: MetaPhlAn did not detect any microbial taxa in the sample.

I installed the corresponding up-to-date database according to the user manual, but I wonder why no metaphlan results are empty, no way to compare to any known microbe, which is not normal, right? I’m using fasta files.

Hello,
Thank you for the great tools. I am using the same version I get the same error after running a couple of tests on a smaller batch of samples.
However, I am able to see in the same samples some PCR-validated bacterial taxa using MEGAN6, using both reads and contigs.
Any idea how this lack of detection could be verified?