Dont know what to do next... Checked for omission, naked and hidden pairs and singles and also couldnt find xy wings, x wings or "unique rectangulars". What do i miss?
R8C5 has a pencil mark for 9, but there is already a 9 in B8 at R9C4. Once that pencil mark is removed, there is only one cell in C5 that can contain 9. The puzzle continues with singles to the end.