First thank you colorlib team for this ultra functional theme
I have similar problem as many as Illdy users with images not showing. I’ve search this forum tried a lot of solutions (adding images again, adding all description fields, disabling pluggin, downgrading and upgrading wp, with and without pluggin galleries…) but still something is wrong in “pages” with images.
Depending on browser, IP, images are loading differently, here 2 examples:
As a first step, I would delete the current photos from both gallery and media and re-upload new ones, maybe with smaller size.
On the other hand, I would sincerely recommend trying some other gallery plugin.
There are so many out there it would be unfair to recommend one, it gets down to trial and error.
You could follow the lead and fix this one if it’s doing the trick in particular, but you should try some other solution to check if the problem persists.