Apple Pencil on 2017 iPad Pro no longer accurate

Have you tried a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons?

There is the possibility that there maybe something wrong with the Apple Pencil.

If you have an Apple Store or Apple reseller close to you, bring both your iPad and Pencil and try a new Pencil on your iPad to see if the issue goes away, or not.

It is worth a shot just to make sure it is not your iPad Pro or your current Apple Pencil.

Best of Luck to You!

Try forgetting the Apple Pencil in the Bluetooth settings and try re-pairing the Pencil.

This is all I got left to try.

Made sure the tip is screwed on securely?

If still no joy.

We are pretty close to the end of the line for iOS 12 updates.

The best you can do is alert Apple to this potential issue.

The only way to get Apple to, DIRECTLY, listen to you is to use their feedback portion of their website.

iPad Feedback

http://www.apple.com/feedback/ipad.html

Cognizant Apple employees read ALL feedback generated from all of the various feedback pages and transfers the data to the proper and responsible Apple teams and personnel , but NO Apple employees will ever respond with any type of direct, individual replies from the feedback you post.

The more users that post product feedback about any product issue, the faster Apple is made aware and starts working on a fix/solution for a quick and future software update.

Also, you may want to phone contact Apple, directly in Cupertino, California, and calmly talk to an Apple customer service employee about this issue via the link below.

https://www.apple.com/contact/

Best of Luck to You!

I doubt there's anything wrong with your pencil. The fact you are touching the screen with another object (a ruler, book, etc.) is causing the issue with the pencil being recognized while trying to draw the straight line.

Look,

When you lay another object, like a ruler or some other physical object down on tne iPad’s screen to draw straight lines or any other geometrtic shapes by hand, that object laying down on the screen is interfering with the hardware in the iPad's screen that controls how the Apple Pencil or any smart Bluetooth stylus reacts/responds.

You maybe, also, causing interference with the iPad's or the particular app's own palm rejection features by confusing it by placing other objects down on the iPad's screen.

I think this is what is actually happening.

You are confusing the iPad by using the pencil and laying another object down on the screen at the same time.

There are lots sketching/drawing/painting apps that have either a software ruler ( like in the default iOS Notes app sketching feature, to draw straight or diagonal lines or some way to be able to accomplish without using an actual object on the iPad's screen.

I believe this is what is causing all of your Pencil issues.

You DO NOT need to use outside objects on your iPad;s drawing to draw anything that involves straight or circular geometry.

The sketching/drawing/paintng apps should have these abilities built into the app.

What iPad model are you using?

What version of iOS are you running?

Have you tried a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons?

Also, I forgot to ask,

Is this iisue happening when the Apple Pencil is using Bluetooth or when the Bluetooth is off and the Apple Pencil is acting more like a “dumb“, standard pointing/touch capacitive-like stylus?