the issue has nothing to do with alt text, you’re serving mixed content. You need to clean that up.
Install the plugin “better search and replace”. Search for https://www.chantal.com and replace with https://www.chantal.com
ixed Content: The page at 'https://www.chantal.com/blog/2016/08/09/the-perfect-dish-for-a-cool-and-delicious-summer/' was loaded over HTTPS, but requested an insecure image 'https://www.chantal.com/blog/wp-content/uploads/2016/08/93-MT20-WT-Angle-e1470761766739-300x195.jpg'. This request has been blocked; the content must be served over HTTPS.
3(index):1
Mixed Content: The page at 'https://www.chantal.com/blog/2016/08/09/the-perfect-dish-for-a-cool-and-delicious-summer/' was loaded over HTTPS, but requested an insecure image 'https://www.chantal.com/blog/wp-content/uploads/2016/08/cucumber-e1470758618972-300x207.jpg'. This request has been blocked; the content must be served over HTTPS.
(index):1
Mixed Content: The page at 'https://www.chantal.com/blog/2016/08/09/the-perfect-dish-for-a-cool-and-delicious-summer/' was loaded over HTTPS, but requested an insecure image 'https://www.chantal.com/blog/wp-content/uploads/2016/08/Ramon-Gonzalez-Tomatoes.jpg.650x0_q70_crop-smart-300x200.jpg'. This content should also be served over HTTPS.
3(index):1
Mixed Content: The page at 'https://www.chantal.com/blog/2016/08/09/the-perfect-dish-for-a-cool-and-delicious-summer/' was loaded over HTTPS, but requested an insecure image 'https://www.chantal.com/blog/wp-content/uploads/2016/08/700544972_564e118f79-300x199.jpg'. This request has been blocked; the content must be served over HTTPS.
(index):1
Mixed Content: The page at 'https://www.chantal.com/blog/2016/08/09/the-perfect-dish-for-a-cool-and-delicious-summer/' was loaded over a secure connection, but contains a form which targets an insecure endpoint 'https://oi.vresp.com/?fid=f251f49965'. This endpoint should be made available over a secure connection.
