Thumbnails do not always load on item page when MediaViewer enabled

[recived]

Describe the bug
Dspace >=7.6.0. Tested in local server, demo.dspace.org, testrephip.unr.edu.ar. If the item page has not been visited for a long time , then the thumbnail does not load (page needs to be refreshed or open in new window). Full item page is ok. I suspect the problem is in the media viewer.

[recived]

/src/app/item-page/media-viewer/media-viewer.component.html, after removing <div class="media-viewer" *ngIf="!isLoading"> partially solves the problem. Thumbnails load fine, animation is playing.

or temporary solution dspace-angular/src/app/item-page/media-viewer/media-viewer.component.ts

    this.thumbnailsRD$ = this.loadRemoteData('THUMBNAIL');
    if (this.thumbnailsRD$) { 
      this.isLoading = false;
    }

[tdonohue]

Pulled this over to the 7.6.x maintenance board. Needs a volunteer to investigate & create a PR to fix.

[mspalti]

We are seeing this issue fairly consistently in 7.6.1. Adding manual change detection seems to fix the problem #2673

[recived]

We are seeing this issue fairly consistently in 7.6.1. Adding manual change detection seems to fix the problem #2673

Thank you. problem solved.

[tdonohue]

I was able to reproduce this locally in the following scenario (Not sure if this is a common scenario, but I wanted to point it out as well):

1. Enable MediaViewer
2. Visit an Item page for an Item that has a Thumbnail from a PDF Bitstream. Thumbnail doesn't load.
   • However, I've found when the Item has a thumbnail created from an image Bitstream, it will oftentimes load properly. (At least I've found it harder to reproduce in this scenario.)

In any case, I've found that @mspalti 's small fix in #2673 also works for me.

[tdonohue]

Closing, fixed by #2673