Exporting to PNG with fonts >73pts - Cant read the PNG

Hi all

While exporting text over 73 pts, the PNG file is unreadable:

I am using a font Clarendon CN BT. I am placing one layer above another. The lower layer I put a stroke on the text to help with a file for embroidery (to cover the small gaps etc.)

If I use a font size of 73 pts I get a good out come. If I go to font size 74 pts or higher, the exported PNG is a big blob of white, the white overtakes the underlying stroke. I Change both layer font sizes.

It still looks good on Photoshop... only when I export.

I have the latest update to Photoshop.

Canvas size 12" x 12"

Text: Clarendon Cn BT (Came with PS)

Works well up to 73 pts. 74 Pts and Over it exports poorly. Even in the export preview window it is unreadable.

Any help would be appreciated as the greater size is important to a project I am doing.

John