sql -129 during a simple select statement

I've got a problem on a system running 4.6c where a statement

SELECT * FROM afvv

         INTO TABLE afvv_tab

         FOR ALL ENTRIES IN aufpl_pre_tab

         WHERE aufpl EQ aufpl_pre_tab-aufpl.

returns an error code SQL -129  (which means sql statement contains too many tables).

It clearly does not contain too many tables in the SQL statement, and there is only one entry in the internal table aufpl_pre_tab.

If I use strsql to execute the statement

select * from afvv where aufpl='<the value from aufpl_pre_tab>'

it returns correctly the 3 entries that it should.

The system has recently been recovered from a backup after a series of disk failures occurred. I'm told the restore was successful and clean.

Does anyone have any idea what could cause this?

[and yes, I know 4.6c is not supported any longer...]