receivers()/disconnect() function always returns 0/false even if there is/was connections

Look at here: 

Even if the "connect()" function do the job and makes the connection (I can verify it since the slots works correctlys in my program and do their jobs), the receivers() function always returns 0.  As well even if there is connection, the disconnect function always returns false even if the disconnection is made !

I give the source code (these functions are in FenPrincipale.cpp file)

In addition in the file SearchDialog.cpp the disconnection totally fails to occurs

Since just after it enters into the slot that should be disconnected :

By changeing only the line disconnect and replacing it by another overloaded disconnect function, and repeating the same protocol (1) it works !

(1): the protocol to repeat the bug is the following: set the breakpoints as in the sceenshots, start debug session, the web navigator will open. Now on any webpage select a word and push "CTRL+F" 

So now to conclude we have three problems at once: 
1) recievers function does not work

2) This function with this prototype "bool QObject::disconnect(const QObject *receiver, const char *method = nullptr) const" always return false, even when it works. 

3) This previous function "bool QObject::disconnect(const QObject *receiver, const char *method = nullptr) const" does not work in some cirumstances. While it's overloaded analog is working.