@Stuart_P , I have tested your image on 3.0.2 and indeed it doesn't work. There is a file not found error trying to open up the image thumbnail.
2023-12-13 21:11:23,939 MainThread openlp.core.ui.servicemanager.ServiceManager ERROR Problem loading service file D:\Users\aqbac\Downloads\Trans-gif-test2.osz
Traceback (most recent call last):
File "openlp\core\ui\servicemanager.py", line 843, in load_file
File "openlp\core\ui\servicemanager.py", line 884, in process_service_items
File "openlp\core\lib\serviceitem.py", line 525, in set_from_service
File "shutil.py", line 418, in copy
File "shutil.py", line 264, in copyfile
FileNotFoundError: [Errno 2] No such file or directory: 'D:\Personal\Church\OpenLPPortable_302_TCE\OpenLPPortable_302_TCE\Data\servicemanager\thumbnails\624c6f56b83130c38a8425f4a7b06fadf8786c6f08249b34399451dc8a223a97.gif'
HOWEVER - the good news in this case is I believe the problem has already been solved by our friends in development, so a fix is in the next version.
OpenLP 3.1.0 Release Candidate 2
Bugs fixed includes - Ignore the thumbnails if the path doesn't exist (fixes #914)
I hope this helps.