Hello all, I arrived to this question because a customer of mine was experiencing the same Issue.
The short version is: go to the column layout specifically on the columns where the values are being converted to 0.00000000000000000000000% and click on the column format window cell, choose the correct format and apply to the column, for me I changed it from ###0.00;(###0.00) to ###0.00%;(###0.00%) on all the affected columns and problem disappeared.
