I0606 02:24:20.047855 26321 init.cpp:342] osquery initialized [version=4.8.0]
I0606 02:24:20.060935 26321 system.cpp:342] Found stale process for osqueryd (25571)
I0606 02:24:20.060984 26321 system.cpp:374] Writing osqueryd pid (26321) to /var/run/osqueryd.pidfile
I0606 02:24:20.061036 26321 extensions.cpp:453] Could not autoload extensions: Cannot open file for reading: /etc/osquery/extensions.load
I0606 02:24:20.061105 26321 dispatcher.cpp:78] Adding new service: WatcherRunner (0x55736de65328) to thread: 139660570441472 (0x55736de5f8d0) in process 26321
I0606 02:24:20.061705 26322 watcher.cpp:593] osqueryd watcher (26321) executing worker (26323)
I0606 02:24:20.071314 26323 init.cpp:339] osquery worker initialized [watcher=26321]
I0606 02:24:20.071440 26323 dispatcher.cpp:78] Adding new service: WatcherWatcherRunner (0x55bf5f62cff8) to thread: 140624141027072 (0x55bf5f62b920) in process 26323
I0606 02:24:20.071499 26323 rocksdb.cpp:132] Opening RocksDB handle: /var/osquery/osquery.db
I0606 02:24:20.130610 26323 dispatcher.cpp:78] Adding new service: ExtensionWatcher (0x55bf5f6c16c8) to thread: 140623428429568 (0x55bf5f644d30) in process 26323
I0606 02:24:20.130664 26323 dispatcher.cpp:78] Adding new service: ExtensionRunnerCore (0x55bf5f6bcf48) to thread: 140623436822272 (0x55bf5f644d10) in process 26323
I0606 02:24:20.130707 26323 tls_enroll.cpp:70] TLSEnrollPlugin requesting a node enroll key from: <https://url/api/v1/osquery/enroll>
I0606 02:24:20.130699 26422 interface.cpp:270] Extension manager service starting: /var/osquery/osquery.em
I0606 02:24:20.130883 26323 smbios_tables.cpp:105] Reading SMBIOS from sysfs DMI node
I0606 02:24:20.132273 26323 smbios_tables.cpp:105] Reading SMBIOS from sysfs DMI node
I0606 02:24:20.132441 26323 tls.cpp:255] TLS/HTTPS POST request to URI: <https://url/api/v1/osquery/enroll>
{"enroll_secret":"secret","host_identifier":"ip-10-40-230-156","platform_type":"9","host_details":{"os_version":{"_id":"18.04","arch":"x86_64","codename":"bionic","major":"18","minor":"04","name":"Ubuntu","patch":"0","pid_with_namespace":"0","platform":"ubuntu","platform_like":"debian","version":"18.04.5 LTS (Bionic Beaver)"},"osquery_info":{"build_distro":"centos7","build_platform":"1","config_hash":"","config_valid":"0","extensions":"inactive","instance_id":"4b40b9d1-6d7a-45fa-ac77-b0571a26f982","pid":"26323","platform_mask":"9","start_time":"1622946260","uuid":"ec25b55a-141e-3530-3124-1322c112a3d1","version":"4.8.0","watcher":"26321"},"platform_info":{"address":"0xf000","date":"10/16/2017","extra":"","revision":"1.0","size":"65536","vendor":"Amazon EC2","version":"1.0","volume_size":"0"},"system_info":{"board_model":"","board_serial":"","board_vendor":"Amazon EC2","board_version":"","computer_name":"ip-10-40-230-156","cpu_brand":"Intel(R) Xeon(R) Platinum 8275CL CPU @ 3.00GHz\u0000\u0000","cpu_logical_cores":"8","cpu_microcode":"0x5003005","cpu_physical_cores":"4","cpu_subtype":"85","cpu_type":"x86_64","hardware_model":"c5.2xlarge","hardware_serial":"ec25b55a-141e-3530-3124-1322c112a3d1","hardware_vendor":"Amazon EC2","hardware_version":"","hostname":"ip-10-40-230-156.ec2.internal","local_hostname":"ip-10-40-230-156.ec2.internal","physical_memory":"16304521216","uuid":"ec25b55a-141e-3530-3124-1322c112a3d1"}}}

W0606 02:24:20.158818 26323 tls_enroll.cpp:77] Failed enrollment request to <https://url/api/v1/osquery/enroll> (No node key returned from TLS enroll plugin) retrying...

I see no errors with the certificates and double checked that the secret being sent is what is being displayed in the fleet gui.

Is it the correct enroll secret? If you run osquery a bit longer do you see the repsonse it got from the server?