'Unsaved data will be lost' in UDO

Dear Experts,

I have created simple UDO which is based on two tables (one of type 'Master Data' and second of type 'Master Data Row'), there is just one UDF in each table.

When i open this UDO from menu and switch form to find mode, i'm receiving alert 'Unsaved data will be lost. Do you want to continue without saving?'. There is no data i entered before mode switching and there is no FMS or active addons in this moment.

After that if I answer 'Yes', switch back to add mode and then switch to find mode again, no alert appear.

How i can avoid this behavior?

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Thanks,

Alexander