String key value is not reset when changing key

[pdesoyres-cc]

Reproduce with:

• have 3 string keys 'key1', 'key2', 'key3'
• each keys with empty value
• select 'key1'
• change value to '111'
• select 'key2'
• value displayed is still '111' although it should be empty
• select 'key3'
• value displayed is still '111' although it should be empty
• select 'key1' back
• select 'key2'
• value is an empty string as it should have been on previous steps