Created attachment 77738 [details]
A sample .ods file
In my Calc spreadsheets I use to format cells so the negative numbers appear as red (Format/Cells.../Category: Numbers and then I check “Negative numbers red”). I had no problem with all negative numbers using Calc up to version 220.127.116.11.
In Calc 4.0.x, if the negative number is the result of a function (i.e. the subtraction of two cells), when Ι save the file and open it again, the color of the number turns to black (default). [See Calc_4.0.x_Sample.ods and Calc_4.0.x_Sample.ods.pdf]
Strangely the problem appears only if Ι use the .ods file type. If i save the same file as .xls and open it again, all negative numbers have red color. [See Calc_4.0.x_Sample.xls and Calc_4.0.x_Sample.xls.pdf]
I confirmed the problem using Calc 4.0.x in several O.S. (Mint13/MATE - Mint14/Cinnamon - Ubuntu12.04/Unity - Win7 Gr Home Premium).
Operating System: Linux (Other)
Version: 18.104.22.168 release
Created attachment 77739 [details]
The .ods file printed as .pdf
Created attachment 77740 [details]
A sample .xls file
Created attachment 77741 [details]
The .xls file printed as .pdf
Hello karatzes thank you for your bug report, this is a well know bug there for I will report set is as a Duplicate.
*** This bug has been marked as a duplicate of bug 60215 ***