Ascendance of a bookworm, search "in Print" filter is missing spin-off

[Ekun]

Hello,

As the tittle topic said, I've just noticed hat the "Ascendance of a bookworm (AoB)" series, when searching with the "in Print" filter, the results are missing parts.
And they're displaying only;
~ the main novel series,
~ the manga adaptation,
~ and the Fanbooks.

While already are in Print too:
"AoB, Short Story Collection", 1 & 2
"AoB, R.A. Stories - First year" &
"AoB, Hannelore's, fifth year @ the R.A." Volumen #1

so, those three titles are missing from the results if trying to filter the series search by this "in Print" filter.

Cheers.