Created attachment 154687 [details] Spreadsheet showing problem. Applying the Error Style to -ve numbers, originally formatted with -ve numbers Red, does not change from Red to White. Hence numbers cannot be seen in the cells. All other text & numbers are changed from black to white. I attach a spreadsheet which shows the problem. I formatted Colunbs B & C as numbersb B2:C2 without ticking the -ve number Red Box B3:C3 with -ve numbers Red box ticked. I copied B2:C3 to B4:C5. Then applied the Error Style to A4:C5. All the text & numbers changed, as expected to white, except C5 which appears to have been kept as Red. With a Red background the number does not appear.
Right-click such directly formatted cells and select Clear Direct Formatting. Styles will not override direct formatting. For this reason, it is not recommended to mix direct formatting and styles!