[Plugin: Polylang] Conflict on upgrading Sliding Door theme

Currently putting together a site to be seen in four languages.
“Polylang v 0.8.9” is brilliant. Easy to use and worked a treat until…

…I upgraded my theme “Slidingdoor” to version 3 .0 .3

The menu dropdowns don’t work in conjunction with the WordPress “Menu” and the Polylang “Menu Language” options. First level menus are fine, sub menus are absent.

They all worked fine on the previous issue of Slidingdoor.

I’m not a coder but I’m comfortable messing – I can see or find nothing to change.

I’m wondering if you have any idea how I can recover the dropdown functionality? If you think you can, please let me know what YOU need to know from me.

Thanks a million.

https://www.ads-software.com/extend/plugins/polylang/