My Spouse Visa (CR1) for the USA is stamped in my UK passport as an MIV (modernised immigrant visa) i.e. it is electronic so I didn't need a sealed packet when I entered USA in July 2018. I've had to fly back to the UK because my mother is ill but my Green Card hasn't arrived. I was not allowed to fly back today because apparently the stamp in the passport says the IV expired in December 2018. I thought I had automatic permanent residence for four years and can't understand how or why the visa expired and why I wasn't told. I am now worried that I'll have to apply for the visa all over again even though it's already been granted. Does anyone have any suggestions. Can I chase the Green Card still and get back with that?
Normally, your immigrant visa will say "Upon endorsement, serves as temporary I-551 evidencing permanent residency." If it does, then it is your temporary green card (I-551) until July 2019.
"Endorsement" refers to the admission stamp placed in your passport on or near the immigrant visa when the CBP officer processes you for immigration. This will have the date on which you immigrated in July 2018.
If the ground staff checking you in are not aware of this, you can explain it to them. Tell them to look in TIMATIC, which says (among other things) that you do not need a visa if you have
an ADIT stamp, (Upon endorsement, serves as temporary I-551 evidencing permanent residency), on a passport or on a Form I-94.
If your visa does indeed say this then you should demand denied boarding compensation from the airline.