MARC 008 (Material Type) doesn't stay what has been selected. Creating a lot of cataloguing records for journal citations, so changed Leader > Position 7 to "B - Serial component part". We then changed MARC 008 > Material Type to "BKS - Books" and successfully saved the catalogue record (no problem here). However, when we reopened MARC 008, the Material Type keep changing back to "CR - Continuing Resource" instead of remain as "BKS - Books"!
I don't know if you have solved this, but you should probably FIRST change 000 to the appropriate type and THEN change 008
*** This bug has been marked as a duplicate of bug 19419 ***