I assume that the field is a BigDecimal. There has been an issue with them if the first value, which was stored has been a non float number, such as BigDecimal(1). See https://jira.axonivy.com/jira/browse/XIVY-3210https://jira.axonivy.com/jira/browse/XIVY-3463
The bug was addressed with 7.4, 8.0 LTS and on the issue is also a patch file for 7.0.
So I'd advise you to migrate to the latest 7.0.14, apply the pre-liminary patch for bigDecimals and you should be fine.fine.
Please get in contact with our support to get the patch and advise how to apply it.