Default Can flash recovery, can't flash rom.

Hi guys,

I'm a little stuck. I have a HTC One HBOOT 1.44 with TWRP 2.7.0.0 installed. I can flash recoveries (CWM or TWRP) but I cannot for the life of me sideload a ROM. I just did a factory reset so I can't exactly turn it back on. Any ideas?