Recently there was a significant change on object line type: number.
Until now the system would put value 0 into the object line even if it’s kept blank. This was caused by the feature that is converting values entered into number line type to real number so empty value was converted to 0.
This was causing issues with mandatory validation on certain fields because 0 is considered as entered value.
Now this is changed that empty value is not converted to 0 anymore and empty value is saved as empty value. This change is valid in version 2017-06.001 (test 19.05.2017).
If you need to have 0 as empty value in the requests you can achieve this by setting the default value on object line template (sub-line template) to: 0.