Bootcamp Windows 7 disappeared after OS update last night...

You will need Windows Startup Repair. Please also see https://support.microsoft.com/en-us/kb/927392.

Please post the output of

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

Your MBR is incorrect. You have entered 'n' where it should not be entered. Please see the second set of Gdisk steps, and the example below it. I will paste it here again. You need to repeat the second set of Gdisk commands again.

Please post a screen shot when you do this.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers.

1. Sudo gdisk /dev/disk0
2. P (Print list of parts)
3. R (Recover)
4. O (print current Hybrid MBR)
5. H (chooses Hybrid)
6. Partitions numbers to be hybridized: 2 3 4
7. Y (Good for GRUB question)
8. N (part 2 boot flag)
9. N (part 3 boot flag)
10. Y (part 4 boot flag make NTFS bootable partition)
11. O (print current Hybrid MBR)
12. W (Write the new MBR)
13. Y (Yes! write the new MBR)
14. Reboot

Here is sample Q&A for this section. Please notice the Press Enter/Return.

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y

This is incorrect. You are making the same mistake again.

Did you see the following three entries in my example? Please repeat the steps again.

Enter an MBR hex code (default AF): Press Enter/Return

Is Windows now up and running?

Please test switching between the OSes and make good backups of OSX an Windows as a base line.

The OSX volume is now a Core Storage volume as shown by the output of diskutil cs list. The output shows that it is revertible. Please execute the following command on the OSX side in Terminal.

diskutil cs revert disk1

Yes, this only changes the OSX volume and converts it from CS to JHFS+, which has a Windows driver.