Maybe IRS was waiting for the Tax Court to tell it that it could not assess penalties for failure to file a Form 5471.  See today's opinion in Alon Farhy, 160 TC 6.

"Respondent assessed penalties under section 6038(b) against
petitioner without statutory authority to do so. Accordingly, we hold
that respondent may not proceed with the collection of these penalties
from petitioner via the proposed levy."