strange lock (hang)

@site)

I have a big replication so I choose do not use "replication" but recreate mview on target site. for that  I do :

1. create table a.tmp_copy_table from a.mymview
2. create public synonym mymview for a.tmp_copy_table 
3. grant correct right for users
4. drop materialized view a.mymview
   
5. test a select * from mymview (so I use public synonym)  => ok
   
6. launch the creation the mview (create materiali.... as select ...@site).

my problem , during the creation of mview :

1. I can't use my public synonym because it hang (select * from mymview )
2. I can use may directly a.tmp_copy_table .
3. I