Logo Missing after activating SSL

Good day

We have a problem with the Logo of our site after we activated SSL on one of our sub-sites(Sass Online) on our multi-site (AetasFN)(parent domain).

We are currently using Really Simple SSL and WPMU Domain Mapping (link provided) https://ww.wp.xz.cn/plugins/wordpress-mu-domain-mapping/ . After activating the SSL certificate we encountered problems with our Logo,slider images and Footer images. All of our links contained atleast “www.sassonline.aetasfn.co.za” and we were able to solve the problems with the sliders and the Footer images by removing the “.aetasfn.”(parent domain) within the link.

Unfortunately we were unable to remove the “.aetasfn”(parent domain) from our Logo’s link and thus we are unable to fix the logo/mixed content completely.
We did try reuploading the logo in Appearance>Theme options>Main Settings but the image breaks when we upload it here.

We tried fixing the mixed content/logo with “Beter Search Replace” (as discussed in previous support forums found here) but the error did not go away.
Site in question: https://sassonline.co.za/

Regards
Steven

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