Ive filled thousands of tanks and bottles. This is common that the remote does not match the actual float level guage. Trust the float. Now, what about that 1/4- 3/4 thing?
If 80% just a smidge over 75% is full, then shouldnt the guage show 1/3, 2/3, full?
know your tank size. The WC # on it is a weight of LPG if its portable is its capacity of water, so 80% is its capacity in LPG.
On mounted asme tanks, capacity is given in gallons, also in water capacity, so 80% of the gallons capacity in water is the LPG capacity. A common C Mh has 40# tank. about 10 gallons. At 1/4 on the guage, you still have 1/3, or 3,3 gallons.