Do you still have the issue ?
Post some screenshots on the errors that you get along with the url to your website , so that I shall check it.

Thanks.

I am attaching 5 different error screenshots.

https://tsipf.com/wp-content/uploads/2019/04/tsipf.com error 1.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.com error 2.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.com error 3.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.com error 4.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.com error 5.jpg

Also, my host provided the following errors and insists that some of Avada theme files are incompatible (without providing details). Avada, in turn, claims that the errors have everything to do with WordPress and nothing with them… I am so lost.
Errors from my host:
[Tue Apr 09 14:15:08 2019] [error] [client 185.234.218.109] ModSecurity: Access denied with code 406 (phase 1). Operator EQ matched 0 at REQUEST_COOKIES. [file “/usr/local/apache/conf/mod_sec/mod_sec.hg.conf”] [line “933”] [id “900245”] [msg “MSIE 9.0 No Cookie”] [hostname “tsipf.com”] [uri “/wp-login.php”] [unique_id “XKzhLBdbRhkABMv6c9kAAAAw”]
[Tue Apr 09 15:46:52 2019] [error] [client 66.69.121.186] , referer: https://tsipf.com/wp-admin/media-new.php
[Tue Apr 09 15:46:52 2019] [error] [client 66.69.121.186] libgomp: Thread creation failed: Resource temporarily unavailable, referer: https://tsipf.com/wp-admin/media-new.php
[Tue Apr 09 15:46:52 2019] [error] [client 66.69.121.186] Premature end of script headers: media-new.php, referer: https://tsipf.com/wp-admin/media-new.php

I have already tried ALL of the recommended things from this thread: https://www.wpbeginner.com/wp-tutorials/how-to-fix-the-http-image-upload-error-in-wordpress/, but nothing helped. I would enormously appreciate any help with this nuisance.

https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror1.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror2.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror3.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror4.jpg
https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror5.jpg

The other screenshots , I don’t understand them clearly

https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror3.jpg
This is another error page I am getting.

https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror4.jpg
Not sure if it is helpful, but, in my cPanel, there are tons of thumbnails being generated while none of them are available to insert in the Media section of WordPress.

https://tsipf.com/wp-content/uploads/2019/04/tsipf.comerror5.jpg
This is to show that one of the uploaded images still do not have any editing options, as usual. There would normally be options to Edit the image within the Media.

I forgot to mention that I am also getting the HTTP error regularly.