I strongly believe this is part of your problem. Historically, the “Have Parent Object” functionality is very hit-or-miss (see this post). Instead, try removing that property from your test object, create a new test object that locates the parent frame, and handle switching to it yourself as a separate test step, like this:
WebUI.switchToFrame(findTestObject('path/to/iframe/object'), 10)
assert WebUI.verifyElementPresent(findTestObject('path/to/my/object'), 10)
Note: If the particular iframe that the element in question lives in is further nested in other iframes, you will of course need multiple switchToFrame() calls to get down to the correct one.