Understood cwatson50. There is also a setting in Mac Mail that sets your preference for attachments without having to decide with each one you forward.
With the Mail app open choose Edit > "Include Attachments With Replies”. Then select which option works best for you. See if that gives you the results you expect.
If you’re still unable to reply with the full photo attached, please restart your Mac in safe mode and test the issue. Here’s how: How to use safe mode on your Mac - Apple Support.
How to use safe mode
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
Apple silicon
1. Shut down your Mac.
2. Turn on your Mac and continue to press and hold the power button until you see the startup options window.
3. Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”
4. Log in to your Mac. You might be asked to log in again.
Intel processor
1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.
2. Release the key when you see the login window, then log in to your Mac.
3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window.
We also want you to be aware that restarting in safe mode may take a bit longer than usual since it prevents some software from loading and does a check of your startup disk. You may also see some graphic anomalies on your screen as well.
Once your Mac is in safe mode, test the issue. Whether or not it happens while in safe mode, restart your Mac normally to exit.
If it didn’t happen while in safe mode, test again after the normal restart.
Please let us know the results when you're able.
All the best.