If something is not tested with P5, the merchants should make a note of it, or the MP staff should flag the product to identify them. There are some things that have problems in P5, but no problems in P4, or require special adjustments. Some items need special adjustments to work properly in P5. P5 testing isn't done here on all products by either the vendors or the MP staff. Assuming that something will work in P5 since it works in P4 doesn't hold true.