Error in mutiple update on v9.1.1

Hello,
I encountered some strange behavior in version 9.1.1 which could be due to a bug.
I wanted to change the reference product for many product versions, so I thought about using the multiple update to do this. However, the new product appears to be incorrectly selected. I am attaching an image where you can see the sequence of the actions performed (black numbers) and the result. The same behavior can also be obtained using the new graphical interface.
There is no trace of errors in the javascript console, neither in the last log on file.
Regards

Hello. Many thanks for answering also on Sunday, your help is unmatched!

I apologize if I was not too clear in the description.
Here's what happens:
1) I have a few dozen products inserted in the system

2) I have 15 "product versions" linked to ProductA to which I want to change the product to ProductB

3) I select the "Multiple updates" icon, then I select the 15 "product versions" to which I want to modify the Product. This screen is probably abnormal, because in the listbox I only see one product but I have many


4) I click on the search icon, the product search popup opens, select the ProductB and then click the selection flag at the top left 
 

5) When the popup closes, I would expect to see my ProductB appear in the listbox, but it is not, the listbox where the new product to assign should probably appear does not change
 

Let me know if I can help you in some other way to better describe what happens.
Regards
 

Really many thanks for taking care about this.
Regards