In Applications Manager version 8, scheduling will not exceed December 31st, 2020. This is not a limitation of of the Java Web Client or a setting in the database that can be changed.
This behavior is a limitation of Applications Manager version 8 which had an End of Support date of March 31st, 2018.
No additional builds of version 8 will be released.
Upgrade to Applications Manger version 9 which has it's scheduling end date increased to December 31st, 2040.