Marvel's Agents of S.H.I.E.L.D.: Season 2 BluRay

Was it ever explained why Marvel/ABC/Disney never released the later seasons on DVD/BluRay?

They did, but not in the USA. No one knows why.

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[*]Marvel’s Agents of S.H.I.E.L.D.: The Complete Third Season

[*]Marvel’s Agents of S.H.I.E.L.D.: The Complete Fourth Season
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