It looks like, i have no errors (log below). But yes, i have a filebeat instance (different docker container) which has ILM enabled. I shut it down for test purposes and restartet everything but no change.
2020-03-02T16:59:02.640Z INFO instance/beat.go:622 Home path: [/usr/share/filebeat] Config path: [/usr/share/filebeat] Data path: [/usr/share/filebeat/data] Logs path: [/usr/share/filebeat/logs]
2020-03-02T16:59:02.666Z INFO instance/beat.go:630 Beat ID: ad1f8f26-d393-4574-990d-84902125f5ed
2020-03-02T16:59:02.666Z INFO [seccomp] seccomp/seccomp.go:124 Syscall filter successfully installed
2020-03-02T16:59:02.666Z INFO [beat] instance/beat.go:958 Beat info {"system_info": {"beat": {"path": {"config": "/usr/share/filebeat", "data": "/usr/share/filebeat/data", "home": "/usr/share/filebeat", "logs": "/usr/share/filebeat/logs"}, "type": "filebeat", "uuid": "ad1f8f26-d393-4574-990d-84902125f5ed"}}}
2020-03-02T16:59:02.666Z INFO [beat] instance/beat.go:967 Build info {"system_info": {"build": {"commit": "6a23e8f8f30f5001ba344e4e54d8d9cb82cb107c", "libbeat": "7.6.0", "time": "2020-02-05T23:06:45.000Z", "version": "7.6.0"}}}
2020-03-02T16:59:02.666Z INFO [beat] instance/beat.go:970 Go runtime info {"system_info": {"go": {"os":"linux","arch":"amd64","max_procs":2,"version":"go1.13.7"}}}
2020-03-02T16:59:02.667Z INFO [beat] instance/beat.go:974 Host info {"system_info": {"host": {"architecture":"x86_64","boot_time":"2020-02-20T08:30:19Z","containerized":true,"name":"b26d74cfe55b","ip":["127.0.0.1/8","172.24.0.3/16"],"kernel_version":"4.9.0-9-amd64","mac":["02:42:ac:18:00:03"],"os":{"family":"redhat","platform":"centos","name":"CentOS Linux","version":"7 (Core)","major":7,"minor":7,"patch":1908,"codename":"Core"},"timezone":"UTC","timezone_offset_sec":0}}}
2020-03-02T16:59:02.668Z INFO [beat] instance/beat.go:1003 Process info {"system_info": {"process": {"capabilities": {"inheritable":["chown","dac_override","fowner","fsetid","kill","setgid","setuid","setpcap","net_bind_service","net_raw","sys_chroot","mknod","audit_write","setfcap"],"permitted":null,"effective":null,"bounding":["chown","dac_override","fowner","fsetid","kill","setgid","setuid","setpcap","net_bind_service","net_raw","sys_chroot","mknod","audit_write","setfcap"],"ambient":null}, "cwd": "/usr/share/filebeat", "exe": "/usr/share/filebeat/filebeat", "name": "filebeat", "pid": 1, "ppid": 0, "seccomp": {"mode":"filter"}, "start_time": "2020-03-02T16:59:01.130Z"}}}
2020-03-02T16:59:02.668Z INFO instance/beat.go:298 Setup Beat: filebeat; Version: 7.6.0
2020-03-02T16:59:02.668Z INFO elasticsearch/client.go:174 Elasticsearch url: http://192.168.128.172:9200
2020-03-02T16:59:02.668Z INFO [publisher] pipeline/module.go:110 Beat name: b26d74cfe55b
2020-03-02T16:59:02.669Z INFO [monitoring] log/log.go:118 Starting metrics logging every 30s
2020-03-02T16:59:02.669Z INFO instance/beat.go:439 filebeat start running.
2020-03-02T16:59:02.669Z INFO registrar/migrate.go:104 No registry home found. Create: /usr/share/filebeat/data/registry/filebeat
2020-03-02T16:59:02.669Z INFO registrar/migrate.go:112 Initialize registry meta file
2020-03-02T16:59:02.683Z INFO registrar/registrar.go:108 No registry file found under: /usr/share/filebeat/data/registry/filebeat/data.json. Creating a new registry file.
2020-03-02T16:59:02.698Z INFO registrar/registrar.go:145 Loading registrar data from /usr/share/filebeat/data/registry/filebeat/data.json
2020-03-02T16:59:02.698Z INFO registrar/registrar.go:152 States Loaded from registrar: 0
2020-03-02T16:59:02.698Z INFO crawler/crawler.go:72 Loading Inputs: 2
2020-03-02T16:59:02.698Z INFO log/input.go:152 Configured paths: [/usr/share/filebeat/logs/logs.json]
2020-03-02T16:59:02.706Z INFO input/input.go:114 Starting input of type: log; ID: 13050393368472405405
2020-03-02T16:59:02.706Z INFO log/input.go:152 Configured paths: [/usr/share/filebeat/logs/logs_business.json]
2020-03-02T16:59:02.706Z INFO input/input.go:114 Starting input of type: log; ID: 5255105000941106788
2020-03-02T16:59:02.706Z INFO crawler/crawler.go:106 Loading and starting Inputs completed. Enabled inputs: 2