Sounds like you have a classic case of the BootStrap script library being loaded by tour WordPress theme.

If this is the case – as several threads within these forums will describe – BootStrap is NOT a supported WordPress script library and plays havoc with The jQuery UI library which IS the preferred, standard and supported library.

There is a chance that code we have added to our next release may overcome this but untikl it is out with users we can not be sure.

Meanwhile the answer is to ensure that the jQuey UI is loaded AFTER Bootstrap. As I say, there are quite a few threads on this, many of which will offer some solutions, but your first step is to determine if BootStrap IS being loaded and is the culprit.