Cutover not succeeding

When I try to run a migration to add an index on a relatively small table, the cutover never succeeds. I've run it with verbose output, and get the following:
```
2018-12-06 14:43:42 INFO Locking `COMPANY_prod`.`retailers`, `COMPANY_prod`.`_retailers_del`
Copy: 91156/91156 100.0%; Applied: 2; Backlog: 0/1000; Time: 1m35s(total), 39s(copy); streamer: mysql-bin-changelog.002933:13183392; State: migrating; ETA: due
2018-12-06 14:43:48 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:43:48 INFO Looking for magic cut-over table
2018-12-06 14:43:48 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:43:48 INFO Dropping magic cut-over table
2018-12-06 14:43:48 INFO Dropping table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:43:48 INFO Table dropped
2018-12-06 14:43:49 INFO Grabbing voluntary lock: gh-ost.12668.lock
2018-12-06 14:43:49 INFO Setting LOCK timeout as 6 seconds
2018-12-06 14:43:49 INFO Looking for magic cut-over table
2018-12-06 14:43:49 INFO Creating magic cut-over table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:43:50 INFO Magic cut-over table created
2018-12-06 14:43:50 INFO Locking `COMPANY_prod`.`retailers`, `COMPANY_prod`.`_retailers_del`
Copy: 91156/91156 100.0%; Applied: 4; Backlog: 0/1000; Time: 1m40s(total), 39s(copy); streamer: mysql-bin-changelog.002933:13689223; State: migrating; ETA: due
2018-12-06 14:43:56 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:43:56 INFO Looking for magic cut-over table
2018-12-06 14:43:56 INFO Dropping magic cut-over table
2018-12-06 14:43:56 INFO Dropping table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:43:56 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:43:56 INFO Table dropped
Copy: 91156/91156 100.0%; Applied: 4; Backlog: 0/1000; Time: 1m45s(total), 39s(copy); streamer: mysql-bin-changelog.002933:14037660; State: migrating; ETA: due
2018-12-06 14:43:57 INFO Grabbing voluntary lock: gh-ost.12680.lock
2018-12-06 14:43:57 INFO Setting LOCK timeout as 6 seconds
2018-12-06 14:43:57 INFO Looking for magic cut-over table
2018-12-06 14:43:57 INFO Creating magic cut-over table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:43:57 INFO Magic cut-over table created
2018-12-06 14:43:57 INFO Locking `COMPANY_prod`.`retailers`, `COMPANY_prod`.`_retailers_del`
Copy: 91156/91156 100.0%; Applied: 4; Backlog: 0/1000; Time: 1m50s(total), 39s(copy); streamer: mysql-bin-changelog.002933:14381575; State: migrating; ETA: due
2018-12-06 14:44:03 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:44:03 INFO Looking for magic cut-over table
2018-12-06 14:44:03 ERROR Error 1205: Lock wait timeout exceeded; try restarting transaction
2018-12-06 14:44:03 INFO Dropping magic cut-over table
2018-12-06 14:44:03 INFO Dropping table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:44:03 INFO Table dropped
2018-12-06 14:44:05 INFO Grabbing voluntary lock: gh-ost.12685.lock
2018-12-06 14:44:05 INFO Setting LOCK timeout as 6 seconds
2018-12-06 14:44:05 INFO Looking for magic cut-over table
2018-12-06 14:44:05 INFO Creating magic cut-over table `COMPANY_prod`.`_retailers_del`
2018-12-06 14:44:05 INFO Magic cut-over table created
2018-12-06 14:44:05 INFO Locking `COMPANY_prod`.`retailers`, `COMPANY_prod`.`_retailers_del`
Copy: 91156/91156 100.0%; Applied: 4; Backlog: 0/1000; Time: 1m55s(total), 39s(copy); streamer: mysql-bin-changelog.002933:15039450; State: migrating; ETA: due
```

It will repeat this ad infinitum, until I kill it after 3-5 minutes. We _are_ using Aurora, but have RBR set and `run-on-master`. We're able to run other migrations, except for this (relatively) small one, so I'm trying to figure out what possibly could cause this so my debugging can be a bit more guided.

So far, love the tool and the fact I don't have to worry about cleanup after, it's been great for us. Just need to figure out this occasional issue!