Upgrade from MySQL 5.6 to 5.7 failed

Trying to upgrade from MySQL 5.6 to 5.7 on RDS.

PrePatchCompatibility.log includes:

1) MySQL 5.7 preupgrade check to catch orphan table issues
	For the following tables, either the datadir directory or frm file was removed or corrupted.
	More Information:
		https://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting-datadict.html

[table_schema, table_name]
name123, - Check the server logs or examine datadir to determine the issue and correct it before upgrading.

Per link provided:

SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES WHERE NAME LIKE '%#sql%';

There are three tables with names:

'tmp/#sql2d63_22106882_6'
'tmp/#sql2d63_22106882_7'
'name123/#sql-19eb_123727b27'

Per that link the process should be to manipulate .frm files in the file system - clearly that's not available in RDS though.

From other reading, tried to drop the table using:

USE name123;
DROP TABLE  `#mysql50##sql-19eb_123727b27`;

But that fails with:

Error Code: 1051. Unknown table 'name123.#mysql50##sql-19eb_123727b27'

Any ideas how to resolve?