Inconsistent/wrong salt level reading

Salt readings should have gone down in this case instead of up when switching cell type.
I think that the amperage is over the T-3 limit and causing the issue with low salt readings.

I would have expected a High Salt warning, but it was showing low salt for some reason.

The amperage is consistent with a T-9 cell or the salinity is about double the amount that is being reported.
 
Can you count the plates?

Register the equipment with Hayward and then file a warranty claim describing the issue and see what they can do to help.

However, you have to be 100% sure about the actual salinity.

I would want 3 good and consistent tests before I contacted Hayward.

I would want a reading from a K-1766 and from a good salt meter.