mypointofview

U salve my life with this. 

taking the risk of asking the most stupid question: have you chosen "disable" in the IQ menu, page 3/3 auto update custom settings? 
If it's set to disable and you switch off your camera, all your changes of settings will not be saved.
What I usually do: set this point to enable, change the settings, switch the camera off, switch the camera back on. Then change it to disable.
Now all your settings are safely stored!
 
🙈

Welcome to the forum.
This issue shows up now and then, some folks are able to find a solution and some are not
Try a different lens (your local camera store may be willing to help you if you do not have a spare).
Get some quick drying electrical contact cleaner, spray some on a cloth and wipe the contacts on the lens and body a few times and let both dry for an hour or so before before reattaching the lens to the body. Do not get any of the cleaner any where other than the contacts though or you might bring on an entirely different issue, A long time ago, folks would use the eraser on pencils to clean contacts, but it is easy to slip and push the pencil in where it should not go.
If these approaches do not work, you may need to see how much the estimate will be for the cost to repair it and go from there.

@mypointofview

I live in Hungary.
Thank you for your help.

Another idea is to find and contact the official Fuji support...

Sure...
https://www.fujix-forum.com/threads/unable-to-restore-camera-settings-using-xapp.142919/#post-1296485

I've reinstalled the XApp on my phone and still can't restore the settings, what I just saved.

Yes, but I've narrowed down to X-E4 the search... Maybe I should find this issue for any camera.
There were no results.

Based on your earlier comment, I dusted off the Fuji X App that I had on my iPhone — uploaded a fresh version, and figured out backup/restore with the Fuji X App.  And, as you say, IT WORKS.  I’m sure that I’ll keep several flavors of settings handy as you have done. But the reason that I really wanted to make backup/restore work is because I have, and shoot with, two X-T4s.  And it is very handy to have the same settings on both cameras.  Thanks to your emails, I have purged Fujifilm X Acquire from all my systems and now climbed in bed with Fuji X App.  Many thanks for your help.  And if sometime you find yourself resting, have a look at WWW.TOMCARROLLPHOTOGRAPHY.COM
Thanks again
TC

Many thanks for your reply.  I do use a. MacBookPro with FUJIFILM X ACQUIRE.   And as you suggest, I have made sure that X ACQUIRE has access to all PHOTOS and FILES AND FOLDERS.  Also, all of my X-T4 and X100V and ACQUIRE software and firmware is up to date.  NO JOY.  All  I see is BACKUP DATA LOAD ERROR.  I have not tried iPhone backup — I’ll give that a try.  Fuji makes such beautiful cameras and such God-awful software.  Such a pity. Thanks for your input.
TC

My experience above was with the latest version of Acquire. I have a laptop with a version installed last year and a backup file of X-E4 settings created today with that older version could be restored with either version of Acquire.
It seems likely Fuji introduced a bug with the latest version of Acquire, at lest with regards to the X-E4. Too bad there's no way to submit a bug report.

I've encountered this same problem, also on an X-E4. I hadn't had any problems with the camera, I just wanted to test the procedure. Some points:
- I use a PC running Windows
- The version of Acquire is the latest.
- I also own an X-S10 and backup and restore worked fine with that, and I'm using the same cable, etc.