I'm trying to extend my current Windows partition because it has too little space currently. I was triple-booting Windows Kali and Ubuntu but deleted Kali and now have 93GB left. I cannot assign it to Windows for some reason. I have tried extending Windows' partition from within Windows itself and Ubuntu's Gparted. TL;DR: Unallocated space stuck in extended partition, but I want to extend my NTFS/windows partition.
Okay. I fixed it. I'll explain for anyone that might ever come across this. On the GParted screenshot you see /dev/sdb/ extended has a key/lock infront of it. When I clicked info it said the following:
Status: Busy (At least one logical partition is mounted)
Alright. It was because I was booted into my Ubuntu. I burned GParted on a Live CD and booted that. It allowed me to shrink the extended partition and resize the windows/ntfs one.