There have been a couple issues with the 6.5 / CC 2015.5 Lightroom update that I have become aware of and want to bring to your attention.

Mac Permissions Issue

With the CC 2015.5 and 6.5 updates, some Mac users are encountering the following message: “Lightroom encountered user permission issues.”  This issue used to cause hangs and crashes, so now Adobe is pushing this message to notify you to resolve this Mac permissions issue (unfortunately even if it wasn’t actually causing you issues.).  To fix it, follow the instructions in this post from Simon Chen, Principal Computer Scientist of Adobe.

Lens Data Issue

Some users are also finding that their lens data is not displaying properly on files imported after the update. This appears only to be an issue if you filter by lens type (using the Library Filter bar at the top of the grid or in smart collections). If this bug affects you,  when you do a metadata filter on lens type, you’ll see “Unknown Lens”.  (Here’s a tutorial on how to use Lightroom’s Library Filter.)

Users experiencing this issue are still able to apply a lens profile.  Adobe Engineering is looking into this bug – follow it in this forum thread. If you experience this and you need or want to filter by lens, a workaround is to convert your files to DNG using an older version of Adobe’s free DNG converter before you import the files into Lightroom.  Download the 9.4 version of the  DNG converter here: Windows   Mac.

If you would prefer to revert to Lightroom 6.4 / CC 2015.4, follow the instructions in this post, except that after installing 6.0, install 6.4 from that same downloads page instead of 6.1.1.

UPDATE: Once 6.5.1/CC 2015.5.1 is released, you will be able to recover the missing lens information using the following steps:

• Select all affected files
• Write your Lightroom editing work out to the files: in the menu bar in the top left go to Metadata>Save Metadata to File (Cmd/Ctl-S).
• Read the metadata: Metadata>Read Metadata from File.