Table gets broken when put it into expand macro

Issue Summary

When put table into expand macro, the first row of table may get broken.
You need reload page and click expand macro few time to make this happen.
It happens for Chrome/Edge/Firefox by my test.

This is reproducible on Data Center: (yes) 

Steps to Reproduce

1. Create a page
2. Add expand
3. insert a table with 3 rows and columns
4. Save the page
5. Open the page, click expand, it should show normally at the first time
6. Reload the page few times
7. Open another page, then back to expand page again
8. Click expand macro

Expected Results

Table should keep the format

Actual Results

First row of table get broken, as below screenshot.

Workaround

Clear browser cache may fix this temporarily, but it will happen again when you click expand, and reload page few times.