I see this in the error console:
Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/050.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/020.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/011.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/035.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/003.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/005.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/015.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/051.jpg'. This content should also be served over HTTPS.
(index):1 Mixed Content: The page at 'https://philasupplies.com/stamp-collecting-supplies-list/' was loaded over HTTPS, but requested an insecure image 'https://philasupplies.com/wp-content/uploads/2020/03/030.jpg'. This content should also be served over HTTPS.
It looks like several of those are in various OG: meta statements. Try resetting your SEO plugin’s settings.