Knitting knotwork

My most ambitious project since I got back to knitting (aged 72) is the Nevern Throw which is 20 squares of knotwork patterned taken from the Welsh Nevern Cross. The printed charts are too small for my ageing eyes so discovering the KnitCompanion app allows for sections of the charts to be enlarged and and to be numbered. The top part of the pic shows when it works, the bottom part was failing to get it right, either inaccurate counts, or only counting some of the chart.
That said, not long after taking this photo I succeeded but alas don’t know how or why!