impdp stuck on index import

It's not stuck. It just does not print every rebuilded index. You can view status of the process using DBA_RESUMABLE.

select * from dba_resumable;

During the impdp process, it doesn't import indexes, in fact it runs number of CREATE INDEX statements.

There could be various reasons of slow index creations such as inefficient PGA memory allocation and IO performance of underlying storage. Parallel(depending on available server resources-CPU,IO) option could improve performance of index-creation.

How can you debug this?

 select * from dba_datapump_jobs;