Yes it does sound as if your valve is defective. Try turning it back and forth several times and perhaps that may free it.
Hope this helps and if not you may have to replace the fill valve which can be a hard job sometimes.
Best of luck,
2002 Monaco Windsor 40PKD. Marjorie 2.
2015 Equinox V6 Roadmaster tow setup
2019 ALP Adventurer 24DS for the short trips. April, 2021