Yes, the correct storage of the probe is in a saturated potassium chloride solution, because this is the same as the reference solution inside the bulb. Equilibrium must be maintained or the probe will not function correctly. If not stored this way, it must be reconditioned by 2-24 hours immersion in KCl solution, followed by recalibration, before use, and it may be irreparably compromised. Chemistry nerds can elaborate on this, but it appears that the cheap meter came with a very incomplete set of instructions, as all pH meters will have the same fundamental requirements. One could spend a lot of time and money trying to salvage a bargain instrument, only to have it never perform properly, thereby leading to undesirable results in many batches of beer. Perhaps a small upfront investment in a decent meter and learning its proper use would be worthwhile.