After upgrade to 3.6.3 we regularly receiving cloud:checkRegisterStatus exception.
Our instance is properly linked to the cloud, "Cloud Service Privacy Terms Agreement" are checked.

Sync button does not make difference.
Push notification works (not always but they are)
Exception while invoking method cloud:checkRegisterStatus
Error: Not authorized [error-not-authorized]
at MethodInvocation.cloud:checkRegisterStatus (app/cloud/server/methods.js:24:10)
at maybeAuditArgumentChecks (packages/ddp-server/livedata_server.js:1771:12)
at packages/ddp-server/livedata_server.js:1689:15
at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1234:12)
at packages/ddp-server/livedata_server.js:1687:36
at new Promise (<anonymous>)
at Server.applyAsync (packages/ddp-server/livedata_server.js:1686:12)
at Server.apply (packages/ddp-server/livedata_server.js:1625:26)
at Server.call (packages/ddp-server/livedata_server.js:1607:17)
at Object.post (app/api/server/v1/misc.js:262:26)
at app/api/server/api.js:394:82
at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1234:12)
at Object._internalRouteActionHandler [as action] (app/api/server/api.js:394:39)
at Route.share.Route.Route._callEndpoint (packages/nimble_restivus/lib/route.coffee:150:32)
at packages/nimble_restivus/lib/route.coffee:59:33
at packages/simple_json-routes.js:98:9
=> awaited here:
at Promise.await (/opt/Rocket.Chat/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/promise_server.js:60:12)
at Server.apply (packages/ddp-server/livedata_server.js:1638:22)
at Server.call (packages/ddp-server/livedata_server.js:1607:17)
at Object.post (app/api/server/v1/misc.js:262:26)
at app/api/server/api.js:394:82
at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1234:12)
at Object._internalRouteActionHandler [as action] (app/api/server/api.js:394:39)
at Route.share.Route.Route._callEndpoint (packages/nimble_restivus/lib/route.coffee:150:32)
at packages/nimble_restivus/lib/route.coffee:59:33
at packages/simple_json-routes.js:98:9
Exception while invoking method cloud:checkRegisterStatus Error: Not authorized [error-not-authorized]
Receiving this error in logs repeatedly as well
Same for me, Version 3.6.3
I have the same with 3.7.0
I had the same after upgrading to 3.7.0 (from 3.5.2).
Solved it by adding USE_NATIVE_OPLOG=true to the Environment= line on /lib/systemd/system/rocketchat.service (manual installation), as per issue #19082.
EDIT: Nevermind, the error messages still show up, just a bit later after startup. Still, it reduces CPU usage from 100% to ~2%, so if you are having issues with that, it might be worth a try.
looks like it is throwing this error when it shouldn't, looks like this call is being done by non-admins, that's why the "Not authorized" errors..
I do have the same bug (together with https://github.com/RocketChat/Rocket.Chat/issues/18662 / https://github.com/RocketChat/Rocket.Chat/issues/18782 )
also experiencing this error in the logs with version 3.6.0.
Facing this bug on version 3.9.3 right now. As well as the blue banner that asks us to join the push notification service. To clarify, I'm talking about issue #19017 which seems to be related to this issue.
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Exception while invoking method cloud:checkRegisterStatus Error: Not authorized [error-not-authorized]
Receiving this error in logs repeatedly as well