Logstash-active index fails to create due to duplicate indexes that don't exist

[cdloh (Callum Loh)]

I'm having trouble with logstash outputting to elasticsearch and it creating it's logstash index

[2019-07-30T10:41:54,893][INFO ][logstash.outputs.elasticsearch] retrying failed action with response code: 500 ({"type"=>"illegal_state_exception", "reason"=>"index and alias names need to be unique, but the following duplicates were found [logstash-active (alias of [logstash-active/7DjBrHMiQIeE2Im2er5juQ])]"})
[2019-07-30T10:41:54,894][INFO ][logstash.outputs.elasticsearch] retrying failed action with response code: 500 ({"type"=>"illegal_state_exception", "reason"=>"index and alias names need to be unique, but the following duplicates were found [logstash-active (alias of [logstash-active/7DjBrHMiQIeE2Im2er5juQ])]"})
[2019-07-30T10:41:54,894][INFO ][logstash.outputs.elasticsearch] Retrying individual bulk actions that failed or were rejected by the previous bulk request. {:count=>2}
[2019-07-30T10:41:58,442][INFO ][logstash.outputs.elasticsearch] retrying failed action with response code: 500 ({"type"=>"illegal_state_exception", "reason"=>"index and alias names need to be unique, but the following duplicates were found [logstash-active (alias of [logstash-active/rDsm0xmTQj-3JzUPDej87A])]"})
[2019-07-30T10:41:58,442][INFO ][logstash.outputs.elasticsearch] Retrying individual bulk actions that failed or were rejected by the previous bulk request. {:count=>1}

For the life of me I can't get it to create that index. I've double checked and that index doesn't exist at all or an alias like it so I can't tell where this is getting confused. Can anybody point me in the right direction?

/_cat/aliases

.kibana   .kibana_2   - - -
.security .security-6 - - -

/_cat/indices?v


health status index                 uuid                   pri rep docs.count docs.deleted store.size pri.store.size
green  open   .kibana_task_manager  7vYgUxQGRvKF0gqLd5ov6g   1   1          2            0       20kb          7.1kb
green  open   generic-access-active gn2nleMxTX64E_gwf4caWQ   5   1    4455963            0      2.8gb          1.4gb
green  open   .kibana_1             7K9JWtJ3SXO6IBji52kKSw   1   1         10            0     55.2kb         27.6kb
green  open   .security-6           tEGs4UKcRtuAKp3Fdrz4jg   1   1         14            2     81.9kb         41.6kb
green  open   .kibana_2             v7scKepZRXmTUCBGrS1_Vg   1   1         12            0       74kb           37kb

ES version: 6.8.1-1
LS version: 6.8.1-1