You can select an IFL file in the VrayHDRI map but you can't select one of a sequence and tick a box to make Vray know it's an IFL.
Temporary Workaround - On a new material create a bitmaptexture select the hdr, select sequence, then you'll be able to load the ifl into the VrayHDRI.
Temporary Workaround - On a new material create a bitmaptexture select the hdr, select sequence, then you'll be able to load the ifl into the VrayHDRI.
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