Combobox events stopped working

Hi,

Suddenly the Combobox events have stopped working; -specifically its _Change event. When I select a list item it displays but the _Change event doesn't fire. Any ideas why this might be happening?

Not sure it matters but I recently installed VS2017! I reinstalled SP6 to see if it fixed things but NSL!

Please help.

I didn't find the right solution from the Internet.

References

Thanks