Make sure to enable the
Language filtering for AJAX operiations option, under the
WPML -> Languages menu. More information in WPML documentation.
Make sure, that the
WPML Compatibility option is turned ON under the search instance
Advanced Options -> Content panel.
WPML Compatibility option is turned ON, then check make sure the
Use the custom ajax handler option is turned off under the
Ajax Search Pro -> Compatibility & Other settings submenu.