Problem on tickets : product disappears when saving form - by: patrice35

Hello,
We have a problem when saving ticket form : the selected product is not saved
Steps :
- Modify ticket
- Select product + modify description for example
- Save ticket
- Open an other ticket
- Reopen the first ticket => the product is empty (modification of description is ok)

See attached screenshots :
Screenshot1 : before clic on "Save" icon
Screenshot2 : after reopen

There is no error in log file.
Projeqtor version : 5.3.5 (same problem with 5.3.3)
Browser : firefox 47.0 (same problem with Chrome)

Thanks