Maybe that the software doesn't follow the IRS instructions to Form 1310?

Who Must File
You must file Form 1310 if the description in line A, line B, or
line C on the form above applies to you. For more details on
these descriptions, see Line A, Line B, and Line C, later.
Don’t file Form 1310 if you are claiming a refund on behalf of
a deceased taxpayer, and:
• You are a surviving spouse filing an original or amended joint
return with the decedent; or
• You are a personal representative (defined later) filing, for the
decedent, an original Form 1040, 1040-SR, 1040-NR, or
1040-SS that has the court certificate showing your
appointment attached.
Example. Assume Mr. Green died on January 4 before filing
his tax return. On April 3 of the same year, you were appointed
by the court as the personal representative for Mr. Green’s
estate and you file Form 1040 for Mr. Green. You do not need to
file Form 1310 to claim the refund on Mr. Green’s tax return.
However, you must attach to his return a copy of the court
certificate showing your appointment.