Many RV water pumps don't 'suck' very well. Try lowering the level of the antifreeze the pump is trying to suck in and pour some antifreeze into the hose so the pump isn't dry when it tries to suck.
Let us know how it goes. Including the year and model of your hybrid may help get more specific answers from owners with similar units.
Sherm & Terry w/rescue Eydie (min Schnauzer) & Charley (std Poodle)
2015 Jay Flight 27RLS, GY Endurance (E), Days: 102 '15, 90 '16, 80 '17, 161 '18
2006 Ford F350 PSD, 4WD, CC, LB, SRW, Cmpr. pkg, Equal-i-zer 4-p, ContiTrac TR
Full timing: Some will think you're crazy, some will be envious, just enjoy the freedom!