IR 5 approved for father in November but still waiting for green card

[NidhiArora123]

Hi,
My fathers IR 5 got approved in Mumbai, India in November and he was required to enter the US before 12th February in order to activate his green card.
He came for a week however, the immigrant officer did not stamp his passport and neither is his I-94 updated online.
We're still waiting for his green card to physically arrive. Has anyone else been in a similar boat recently ?
Will appreciate any help, thanks.

[newacct]

There was no entry stamp corresponding to his entry on his passport?

[Priya.nka]

Is the IR5 valid only for 3 months?