active or passive voice parallel only in if...then ?

[asker]

The 6th edition of Manhattan Prep SC guide, page 150 said:

As a final note, you do not have to make active or passive voice parallel
throughout a sentence. For example:
Right: The shuttle launch TOOK place flawlessly and WAS SEEN on
television.
Both parallel elements work with the subject of the sentence: The shuttle
launch took place and the shuttle launch was seen on television.

But OG13 edition , problem 114
[deleted because problem is from a banned source - see below]
Official explanation mentioned:
If [active voice], then [active voice]
OR:
If [passive voice], then [passive voice]
cannot mix with active + passive in one if... then sentence.

Another example is problem 40 in OG13 edition:
[deleted because problem is from a banned source - see below]

So does this explanation conflict with Manhattan prep guide?

[tim]

OG is a banned source; it is illegal to post OG questions anywhere on the web. If you are in one of our classes, please ask OG questions during office hours or before/after class.

As to your question, no, there is no conflict. When the GMAT says "doing x is better than doing y", that doesn't mean y is invalid. Additionally, a quick glance at the problem suggested to me that it could be solved without even resorting to strict parallelism rules, so the GMAT's explanation is irrelevant because it is unnecessary. You see this a lot with OG explanations, and in general their SC explanations should be taken with a grain of salt.

[RonPurewal]

the truth is even worse than 'unnecessary'.

the OG answer keys are usually incomplete—and quite often wrong.
the keys are subcontracted to people who are, to be blunt, nowhere near as good as the problem writers. in many cases they just don't know how to explain how, or why, something is incorrect. (to be fair, good explanations are not very easy to find.)

but, please read the forum rules before posting. thank you.