If you've noticed that products' images are not imported, check 'Images to be imported' line at the top bar of your WordPress admin area. Normally, when products import is finished, this number should be equal to '0' . But sometimes, images import is stuck.
How to fix:
1. Disable Cloudflare (if you are using it).
2. Check 3rd party plugins installed on your site (disable all of them, then enable one by one and check if the issue still persists).
3. go to WooCommerce -> Status -> Max upload size and check your 'Max upload size':
If it is 2MB, or less, please contact your Hosting support and ask them to set it to 32MB.
4. Check all other System Statuses in WooCommerce -> Status and check carefully those which are marked in red, like in the example below:
Then contact your Hosting provider support and ask to solve this issue.