Lightning: Find Events not working

Have version 60.2.1 (64-bit) installed from Linux Mint 18.3 repos. Just discovered that clicking on the "Find Events" button in Lightning (or same for menu item) and NOTHING shows in the Find Events panel that appears. That's NOTHING with a BIG capital 'N'. So what happened? How can it be fixed.

FWIW, this is the WORST upgrade of Thunderbird for a l-o-n-g l-o-n-g time. The completely botched management of the add-on aspect was unbelievably incompetent. Lightning f**ked for an awful lot of people with little help until a few folk (outside of Mozilla) started posting "Uninstall add-on, install distrib xul-). Very bad. The sheer number of "Lighting broke" references when searching the web is testament to the appalling approach to pushing the upgrade. Then there are all those really helpful add-on developers out there that are totally p***ed off with the sudden incompatibility of there helpful work because of an unhelpful Add-on API team. Plus, I've got problems (that I didn't have before) with the Date & Time display aspects and they seem to be insurmountable given the wholly arrogant attitude of those developers involved -- just how *does* Thunderbird/Lightning work with locale? I'm genuinely convinced the developers don't know. And don't get me started on CalDav...

I'm thinking I might be better going back to a previous, stable and FUNCTIONAL version. If the next > v60 upgrade version actually fixes all/most of the problems, I might stick with it, but otherwise I think I'll have to find something else. Shame because this really was a f**king great product with a seriously promising future. Sad. Very sad.