Card content not displayed in Power point export

Assuming you are using the Period over Period feature and without know how you filtered the page, I tested this and I didn't experience the problem.  However, one option depending on how you want to visualize is to create a beast mode for previous month and for previous month of the previous year and calculate the YoY difference. This has the benefit of being able to be displayed in a table, which the current Period over Period charts currently do not.  Below is any example I pulled and you may be able to alter for your use.

CASE WHEN (SUM(CASE
WHEN MONTH(DATE_ADD(CURRENT_DATE(), INTERVAL -1 MONTH)) = MONTH(`Date`) AND YEAR(DATE_ADD(CURRENT_DATE(), INTERVAL -13 MONTH)) = YEAR(`Date`)
THEN `<metric>`
ELSE 0
END )) = 0 THEN 0 ELSE

(SUM(CASE
WHEN MONTH(DATE_ADD(CURRENT_DATE(), INTERVAL -1 MONTH)) = MONTH(`Date`) AND YEAR(DATE_ADD(CURRENT_DATE(), INTERVAL -1 MONTH)) = YEAR(`Date`)
THEN `<metric>`
ELSE 0
END)

-

SUM(CASE
WHEN MONTH(DATE_ADD(CURRENT_DATE(), INTERVAL -1 MONTH)) = MONTH(`Date`) AND YEAR(DATE_ADD(CURRENT_DATE(), INTERVAL -13 MONTH)) = YEAR(`Date`)
THEN `<metric>`
ELSE 0
END))

/

SUM(CASE
WHEN MONTH(DATE_ADD(CURRENT_DATE(), INTERVAL -1 MONTH)) = MONTH(`Date`) AND YEAR(DATE_ADD(CURRENT_DATE(), INTERVAL -13 MONTH)) = YEAR(`Date`)
THEN `<metric>`
ELSE 0
END)
END