[2 Search index with different searchable fields exist] Possible bug in 'Flexicontent - Search' module?

I'm experiencing a issue (bug?) in that module
I've set a page where visitors can search items though the whole website.
In that page I've included 3 different 'Flexicontent - Search' modules, each of them having a different custom id menu voice target: in that way I can get different results searching in 4 (four) item types, depending on search types selected in each menu item:

• The first module points to the first menu voice: in that menu voice I have included only the first two "searchable types" values in the "Search Form: Content types" section to get search results filtered by only those 2 types.
• The second module points to the second menu voice, where I have included the other two "searchable types" in the "Search Form: Content types" section.
• The third module points to the third menu voice, where I have included alle the four  "searchable types" in the "Search Form: Content types"section.

But I get non consistent results when using the same search string in the first/second or in the third module.

To verify that, you can go to dev.giulioandreotti.org/cerca , put the word "fuci" into the first search field (the one on top) and hit the search button: you get 7 items (correct)
Go back to the dev.giulioandreotti.org/cerca page and put the same "fuci" word into the second field and hit the search button: you get 4 items (correct)
Go back again to the dev.giulioandreotti.org/cerca page and put the same "fuci" word into the last bottom field and hit the search button: you get 7 items instead of 7 +4=11 (wrong). For that item voice I have set ALL the four search types to be searched, but some of them seems to be excluded in search results.

Can you please address me to a solution?
Waiting for your kindly reply asap.
Regards

Versions: FC 3.2.1.14 - J 3.8.12 - PHP 7.0.27

Hello

so the configuration that you have in the 3rd Search menu item is not behaving as you expected ?

you may send me super admin access via PM and i will check to see if this
is misconfiguration
or if it is bug or even if some parameter is misleading / difficult

OK, thank: sent pm right now

Just a reminder: any news?
Thanks

ps: I have switched to PHP 7.2.9 so now used versions are: FC 3.2.1.14 - J 3.8.12 - PHP 7.2.9

Hello

here is the reason

The first 2 menu items are using "Basic search Index" (same index is used in category views)
The 3rd menu item are using "Advanced search Index"

And you have configured different fields to the 2 search indexes

Either set 3rd menu item to use the "Basic index" too
or go to fields manager and make sure that all searchable fields are set to be added to both indexes
- then you will be prompted to re-index

Thank you for the hint, and sorry for late reply (I've been out for a while...)