One way to tell is to reset the LR Preferences file. I would make a copy of the current one to some other folder then delete the original. Do that with LR closed and the next time LR is opened the preference file will be recreated. If you still have the same thing happen then I guess Adobe set the lens profile to be on for your camera and lens combo.
Just Shoot Me' response is the first thing I would try and what should work, if it does not one workaround to try would be to create a preset with the lens correction turned off and apply it during import and see if that is a viable workaround. To my knowledge Adobe has not made "Enable Profile Corrections" On a default setting.
Apologies for the delay, but thank you very much to the both of you for kindly responding! I have tried resetting the Preferences file, so when Lightroom is launched I am presented with all the initial tour. However, even doing so, when I click on "Reset" in the Develop module, all adjustments are reset but "Enable Profile Corrections" turns on. For photos that were not edited but imported before August 26, 2016, all settings are blank and "Enable Profile Corrections" is off. Once "Reset" is clicked though, "Enable Profile Corrections" turns on. Further, going through my library, the behavior appears to differ depending on the camera/lens combination. The following appears to be what I am experiencing:
Sony A7 + Sony lens: "Reset" => Enable Profile Corrections turns on
Sony A7 + "dumb" adapter + Nikon lens: "Reset" => Enable Profile Corrections NOT turned on
Nikon body + Nikon lens: "Reset" => Enable Profile Corrections NOT turned on
I am beginning to think that sometime after August 26, 2016 Adobe may have changed the default behavior for "Enable Profile Corrections" for at least the Sony A7 + Sony lens combination. Out of curiosity, does anybody from Adobe comment on these forums?
Reset the Develop setting to LR defaults. While in the Develop module go to the Develop menu item then "Set Default Settings" item and in the dialog that comes up click the button that says "Restore Adobe Default Settings".
Thank you very much for your prompt response! I tried resetting the default Lightroom Develop settings by:
Develop > Set Default Settings > Restore Adobe Default Settings
However, afterwards when I click on "Reset" in the Develop module, all edits are indeed reset, but "Enable Profile Corrections" turns on for all of the photos in my library taken with the Sony A7 + Sony lens combination.
See the screen capture for Lightroom Preferences > presets Tab and check if you have the option to make defaults to be Camera and ISO specific. Possible that this may be affecting the develop settings. My lens corrections is not set to on by default.
Just a thought, when you reset the defaults it does not change the previous imports. This is applied at import.