I have spotted this issue on dynamic scaffolding. Did not tried it on static. This issue appeared in Chrome. In IE it behaves without problems.
When I input value bigger than 999 in numeric field (integer, bigdecimal, float), localization settings changes value e.g. from 1111 to 1,111 but on save it is changed to 1 111. This causes that on update, string 1 111 is resolved like non numeric and therefore, value is not filled in field - it stays empty. When entering value with 3 and less digits, everything is ok.