Photo/Video not uploading

Welcome to the Apple Support Communities!

I understand you got on new Windows computer and you want to get the pictures that you have on your iPhone X into it. The first thing I would suggest is to confirm that you have the 2 TB of space in iCloud:
Manage your iCloud storage​
Check your iPhone X to make sure iCloud Photo Library is enabled on it:
iCloud Photo Library
Depending on the number of photos you have, and the speed of your internet connection, it might take a while for the photos to upload to www.icloud.com.
Once the number of photos and videos that you have on your iPhone X matches what is on iCloud, then you can address the syncing between iCloud and your Acer PC. Do you have the most recent version of iCloud for Windows installed?
Set up and use iCloud for Windows
I would highly suggest you create a backup of your photos and videos by importing them directly from the iPhone to your new computer using the Lightning to USB cable that came with it:
Transfer photos and videos from your iPhone, iPad, or iPod touch

Import to your PC

You can import photos to your PC by connecting your device to your computer and using Windows Photos app:

1. Make sure that you have the latest version of iTunes on your PC. Importing photos to your PC requires iTunes 12.5.1 or later.
2. Connect your iPhone, iPad, or iPod touch to your PC with a USB cable.
3. You might need to unlock your iOS device using your passcode.
4. You might also see a prompt on the iOS device asking you to Trust This Computer. Tap Trust or Allow to continue.

Then, follow the steps in these Microsoft knowledge base articles to learn how to import photos to Windows Photos app:

• Windows 10
• Windows 8
• Windows 7

When you import videos from your iOS device to your PC, some might be rotated incorrectly in Windows Photos app. You can add these videos to iTunes to play them in the correct orientation.

Photos and videos that you sync from your computer to your iOS device using iTunes can't be imported back to your computer.

Learn what to do if you can‘t import photos from your iPhone, iPad, or iPod touch to your computer.

Take care.