The batteries are out, just the power cord supplying power.
Since migration I have had this happen to many of my devices. Mostly motion sensors.
I contacted customer service. They sent an email to reboot the hub like I did previously. This time I added fresh batteries as per their recommendation. Previously, I was only using the power cord to power the hub. I added the batteries and rebooted. After a couple of minutes, the hub connected.
I seem to be having issues where all my hue bulbs go online and offline every 4 seconds , and I am unable to control them, if they do response it takes well over a minute
Hopefully zigbee device health is working correctly. this is rolling out today 
I havenāt heard a response to my bug report from Thursday.
@Kianoosh_Karami, two of three of my IKEA Signal Repeaters has went Offline, I believe recently. I have never had any similar issue.
I did a hunt for offline devices yesterday with the new app, and surprisingly two of them were Offline. Unplugging and re-plugging them back make them to show up Online immediately, but it is definitely something weird what I havenāt experienced before.
Otherwise the History of any device in the new app is extremely slow. It takes 5-10 minutes to populate with data, and that is still not up-to-date when some shows up there.
Jimmy, Sorry for the late response. I think we have got your issue squared away. Thanks as always for providing the feedback.
Letās resolve this through DM.
I have a number of Multipurpose sensors offline this evenings, all have good battery levelsā¦
@Kianoosh_Karami @BarryA Guys, is there anyone from Smartthings support reading the support@smartthings.com mailbox?? Iām posting here hopping Iāll get your attention. Iāve ended up with some weird behavior after the forced migration and contacted support multiple times during the past several weeks and monthsā¦ Zero answers. Can anyone from support please help? Pretty much evertthing looks broken in the new app after the migration. Iām still able to do things with the classic one, but I understnad that will be retired. Iāll be left with a completely broken hub that will worth nothing if the classic app will be turned off. These are some tickets numbers where I provided a lot of details: 1015681, 1017673, 1026793 and 1031200. Thank you for looking into this issue.
This is still broken, does anyone I have hue to confirm this issue?
I will check it now, but I havenāt seen any issues with my Hue setup. I can control it through ST and Google Home.
I can control it sometimes, but takes 5 minutes to actually respond
If you havenāt done it yet. Try to reboot your Hue Bridge and check the ethernet connection there.
I have rebooted it, control via hue app, hue switches, Alexa with the hue skill is all perfect, itās via smartthings that has a problem, likely to do with the heltchcheck changes since the lights go available /unavailable every 4 seconds
When I mean reboot, I mean āSwedish resetā, power unplug, count 10 Mississippis, and plug it back.
I have had once similar experience, back then the Bridge was playing up.
And are you using the cloud or lan integration for the Hue?
Lan integrated , il give it a go
No joy, unplugged reset hue, reset smartthings still taking minutes to respond
And the cable sure good and the Bridge has 3 solid Blue LED on?
Yep, and the hue app, and Alexa skill work fine itās specifically an issue when using smartthings