First, if you formatted the card as Internal Storage, reformatting it as Portable Storage will make you lose all of the data on that card (much of which is actually crucial app data, since the phone is using the card as Internal Storage to install apps to).
Second, since the card is formatted as Internal Storage, you shouldn't have any problems saving photos, because the SD card has been incorporated into the phone's overall Internal Storage. You'll still see it broken down into Internal Storage and SD card in the
Settings>Storage menu, but the phone is still regarding both as making up a whole.
Did you actually remove the card after formatting it as Internal Storage? If so, that might have caused some issues. Cards shouldn't be removed after being formatted as Internal Storage, because that'd be like removing one of the internal memory chips--the phone won't like that. Read more here:
http://www.androidcentral.com/inside-marshmallow-adoptable-storage
Are you saying that your phone is telling you there's no more room to save photos?