CaptGeorge, I rarely remaster, and even when I do it's been years since I used the builtin version. Several years ago I discovered remaster-x, https://oldforum.puppylinux.com/viewtop ... =94033&i=1 which --as far as I can tell-- merely restructured the builtin so that you only had to input information at the beginning --taking your time to read instructions-- and was less prone to human error.
Remaster-x remains my 'go-to' application even though (a) amethyst has published nicOS-Utility-Suite, which has remaster tools, https://forum.puppylinux.com/viewtopic ... 106&t=1694 and (b) remaster-x can no longer manage all which needs to be done, consequently requiring human intervention. I think that my human intervention routine may serve in your situation.
What all 'remaster' tools do is leave a folder somewhere. Remaster-x's folder is named /puppylivecd and would be located on your /mnt/home. That's probably also true of the builtin remaster. NicOS's version might be named something else; but similar, perhaps puppybuild or puppytemp. File browse into it and you should find all the file required to create an ISO. But the way to tell is to mount (Left-Click) your source ISO and compare contents.
Remaster-x was created before UEFI, and before the inclusion of adrv.sfs and/or ydrv.sfs in Puppys became common. So while I have the source ISO open, I Left-Press, hold then drag any missing file or folder into the puppylivecd folder and select copy. The result is a folder containing everything needed to create an ISO.
You may want to rename the folder or Right-Click>Duplicate, or just copy its contents into a folder having an appropriate name.
Depending on which Puppy you are running --it doesn't have to be the same as used to create the 'build folder'-- there are a couple of ways to obtain an iso. The easiest, when available, is Right-Click the folder and select dir2iso from the menu. 2nd easiest is to open a terminal adjacent to the folder and enter the command "dir2iso NAME" without the quotes and substituting the folder's actual name for NAME.
Other than that look at your Puppy's Menu>Multimedia sub-menu for either the ISOMaster or the Pburn CD/DVD application. It's intermediate step before burning to media is to create an ISO.