Max Substitute length
Apparently there is a maximum number of characters that can be processed by a substitute. When there are too many characters things like {tab} are ignored. I created a Linked in message which had a subject{tab}body. Everything ended up in the subject field up to the limit of characters allowed in the LinkedIn subject field. I went through my message to ensure I didn't miss a character that needed curly braces. Finally, I figured out it was simply the length. I gave it the readers digest treatment, the verbosity exlax, and voila. I didn't bother counting the total characters that didn't work but it would be somewhat beyond 1375 - the current count which works fine.
Longer texts (default >1500 characters) are sent using Clipboard method which is faster but sends special characters literally (raw).
For your case to work, increase the "Preferences/Text Expander/Use Clipboard if text length exceeds (char)" setting to higher number.
For your case to work, increase the "Preferences/Text Expander/Use Clipboard if text length exceeds (char)" setting to higher number.