I apologize for the delay
I think that the problem is an overflow in .TAB files
It contains position in PCK in which begin the tiles.
The index was momorized by 2 byte (unsigned short).
The max value allowed is 65536.
When the size of pck file grow over that dimesion,
or better when a new tile begin after that position,
the TAB file is corrupted because the index of the new tiled was saved with an overflow
therefore them point on previous tile image at strange, but constant, position.
There is not a solution because it is connect to file format (same problem than maps ...sigh
)
I will add a block in PCKView to limit max number of tiles to avoid the someone loose
time about it.
You, correctly just ipotized that problem was connected with max tile numbers.
TAB file for TFTD Unit have 4 byte slot index.
This option was asked by PCKView before saving: the second option enable it.
I could will correct PCKView/Mapview to recognize the format 2/4 byte index by compare file size with first entry (the tiles count).
But
The MCDEdit sorce code are not public
and
I do not know if OX engine is ables to read them without a fix.
We need a new file formats at list to break the size limits imposed by pc performance of 1994
backward compatibility is mandatory and
all tools and engine could be aligned to support both file formats: (map, pck, tab, mcd) versus (map2, pck2, tab2, mcd2)
An analisy of requirements it is desirable.