The situation in the picture below occurs when solving void cubes – in 50% of cases:

This cube was being solved using a computer, so we repeated the solving (along with the scrambling) from the beginning but on a regular 3x3x3 cube, and we got it:

It turns out that one of the middle layers is rotated once. To complete the solution, simply rotate the middle layer once and finish the solution (for example using the EDGE-CORNERS method). In R:

library(rcube)
set.seed(2)
createCube() %>% scramble() %>% twistCube("fDbdP (rDRDFdf)x1 d
(rDRDFdf)x2 DUUdF2Df2 D2 Fd2fuD2Ld2lD
r2DR2PPU2UUFRRU2rru2fPPodfRRU2rru2FoDD
fRRU2rru2FoofRRU2rru2FDDU2ooRRU2rru2o
U2 f r2 f; RR U2 rr u2; F R2 F O RR U2
rr u2 O (RR U2 rr u2)x2 O f r2 f; RR
U2 rr u2; F R2 F (RR U2 rr u2)x2") %>% plot3dFlat()