I had a few devices on the edge of my network in a detached garage that seemed to not work right a lot. It also seemed to interfere with all the devices and cause slow responses, even ones near the hub . I added a switch on the back porch between the house and garage and things are a lot faster across the whole zwave network.
When you do a zwave repair, do you get any errors? I was getting a lot but dont get any now with the new switch/repeater. I agree with @JDRoberts if its a zwave mesh issue you’ll have that with any hub you use. Also could be “ghost” devices. FAQ: How to remove ghost devices from your z-wave and zigbee networks