transaction log grows despite recovery=simple. SHRINKFILE does not release space

Question

I have this script that restores a DB, sets recovery=simple, trims some tables & shrinks files:

RESTORE DATABASE [ABC] FROM DISK (....)
ALTER DATABASE [ABC] SET RECOVERY simple
go
exec [ABC]..trim

"trim" stored proc is as follows:

CREATE PROCEDURE trim   
AS
TRUNCATE table A
TRUNCATE table B
(...)
DELETE TOP 1000 FROM C where date < @somedate
DELETE TOP 1000 FROM D where date < @somedate
(...)
DBCC SHRINKFILE (N'ABC_Log' , 0, TRUNCATEONLY)
DBCC SHRINKFILE (N'ABC_data' , 0)

Note - each of the "DELETE TOP 1000 FROM D where" is done in a loop until no more rows to delete. This to keep each transaction small.

When I run all of this script manually, step by step all is well - transaction log is kept small, SHRINKFILE truncates the log table to 1KB

When this is executed all as one script, all in one run, this is what happens:

• transaction logs keeps growing (as if recovery=full)
• SHRINKFILE does not truncate the log, long remains 99% empty but huge

Any hints what could be going wrong? Do I need a "GO" placed somewhere?