This issue was fixed in the November 2022 release
issue
When setting a numbered line item to hyphen format. When exporting as xls or xlsx, the hyphen formatted cell will only ever display a hyphen, even when edited to be non zero cell values.
workaround
The only means to workaround this is to remove the custom formatting on the cell in excel until this has been fixed.
If this workaround is not suitable in your use case, please contact our Care team.