UPDATE:I just completely removed WP-Optimize plugin and WPForo buttons are now working. I reinstalled WP-Optimize and left if deactived and WPForo b...

Thank you Chris, I discovered this last night also. Glad it was a simple solution!!

Okay, just found a simple fix. I removed the widget and re-add the widget and now it is working again. Hope this helps others that might have this...

Same here, just updated and noticed it now shows "No online members at the moment". Hope this will be patched asap.