Order download buttons randomly not displaying & attributes controller page issue

These issues may be related?

1. Upgraded shop in November to ZC 1.51 and everthing appeared to be working well. Then recently customers began complaining not seeing the download button for their download product orders. I just logged into a customer account and checked the customers order page in admin. On both pages order status shows shipped (as standard) and download product items are listed with with 4 downloads remaining in next seven days. And in the admin order page, the download product item shows a green button to indicate download item is "available".

I noticed on this particular order, customer ordered three items, two download producs and the other was a physical item. But the download buttons are not displayed in customers MyAccount order history as they should be. (I assume the download buttons also did not display on customers checkout_success page).

I'm suspecting the issue might only apply to orders containing multiple download product items?

2. So in admin I went to double check settings in attributes_controller, but the page appears blank.
   Admin > Catalog > Attributes Controller (attributes_controller.php).

I checked the filedate with the orginal uploaded file from november and it has not changed.

All other admin pages render fine.

FYI, I went ahead and applied the fixes (to three files) listed in this bug fix post
http://www.zen-cart.com/showthread.php?200688-Known-Bugs-%28and-fixes%29-with-v1-5-1&p=1154025#post1154025

But that did not solve either of the above issues.

3. I notice the filename in my ZC151 package is: options_name_manager.php

Whereas the post in bug reports suggests editing a file named:
options_names_manager.php

(NOTE: "name" vs "names")

Which filename is correct? And why would the filename in my ZC151 package be different from the filename listed in the bug fix posting? And could this filename difference be contributing to the above issues?

Thanks for any assist.

Follow-up:

After uploading the three updated files with patched code, the attributes controller page did not display as hoped.

But after I cleared my browser cache, the page did display.

And, knock on wood, the download buttons are now properly displayed as well.

Thanks for the patch code!

And just a heads up...the attachment with the three patched files contained the file with the correct filename: options_name_manager.php

So the two following Bug Reports posts list the INCORRECT filename:

http://www.zen-cart.com/showthread.php?200688-Known-Bugs-%28and-fixes%29-with-v1-5-1&p=1154025#post1154025

http://www.zen-cart.com/showthread.php?200551-Attributes-controller-fatal-error-after-upgrade&p=1153132#post1153132