If I ask only for images to be returned in a search, all is fine. If I ask for albums, news, or pages to be included in search, zpMasonry will only display the number of items equal to the number of thumbnails per page set in the theme options.
The search count in the breadcrumb menu displays the correct number of images that should be displayed.

I honestly don't remember if this worked in 1.41 or not. It does not make any difference if infinite scrolling is on or off. I am using ZenPhoto ver. 1.411 with 7/21 trunk download. Tested this on fresh install of zpMasonry 1.41 theme and cleared cache.

Does this happen in any of the included themes? (ZenPage)

You're right. It may be a Zenphoto issue. With ZenPage enabled and search plugin options set to include content, if I search with all fields selected in dropdown box, only news, pages, and albums are shown - no images at all. If I uncheck the content in the search box, then the images are displayed fine.

In case it matters, my images are selected based on the tag field.

Images (and albums) have no "content", technically they are the content. The field you probably wanted to search is called "description".

I don't think you understand what I was trying to say. If search plugin options are set to include matches from albums, images, news, and pages, I should see matches from all those items.

If I search for orchids and select content, title, tags, and description, the results should display an album named orchids as well as images that are tagged orchids or have orchids in image title or description. If content is checked, it should also return pages that contain the word orchids. E.g. an article like "In Search of the ... Orchid."

Currently, if I select tags and title, I see orchid images as expected. If I select content in addition to tags and title, no orchid images are shown at all.

If necessary I can post a link to a test site to demonstrate.

I just wanted to be sure that no one expects "descriptions" results if the "content" field is checked...;-)

Yes, please post a link.

I have tried to reproduce this on 1.4.1.1 [7817] but everything is working as expected. I even used "orchards" as the tag/title/description/content target.

Visit http://natureinfocus.com/test. I've switched it to the default zenpage theme for now. In search plugin options, I've checked not to return album matches. Search results a bit different than zpMasonry but stll wrong. If you search for orchids (not orchards!) with all search fields ticked, it returns articles that reference orchids but it also returns albums (should not) and no images at all. If you clear search and run it again with only tags checked, it show tagged images correctly.

Hope you can clear up this mystery. I will try to update to latest nightly download in mentime.

JUst tried on your site and I indeed got albums. and an error:
"Fatal error: Call to a member function isDynamic() on a non-object in /home/content/n/a/t//html/test/zp-core/template-functions.php on line 1703"

You may have been there just as I was updating the files to the 7/28 build. With a quick check, the search seems to work with zenPage on that build. I've not seen the error you referenced. Will have to test on the zpMasonry theme again.