I made the following test with LO 5.1.6.2 on Windows 10 x64:
- Created a new spreadsheet.
- Selected A1:C3 → Format → Conditional Formatting → Condition…
- Cell value is equal to 0 → Apply Style → New Style…
- Organizer → Name - blue; Font Effects → Color → blue
- Save as XLSX
- Open with MS Excel (I used 2016) → enter 0 or 1 to A1 or any other in the range
The test shows that conditional formatting applies OK. The color changes depending on entered value.
The same is with newer versions, including current master.
So, either you have some problem with your installation, or there’s some specific details you need to provide.