Melanie J. Delgado Phillips 

I think you simply copied the things you tried from the other thread and didn't make this your own (doesn't look like French (Canada) from your screenshot).  Please confirm:

1. the project languages you're working with
2. the underlying filetype you're translating

Given the red line extends across a bunch of words it does look odd, but let's understand what we're working with first.

The languages I'm using are Spanish (Spain, International Sort) to English (United Kingdom).
I'm translating Word docx files.

Thanks

Melanie J. Delgado Phillips 

Melanie J. Delgado Phillips said:

I'm translating Word docx files.

Were they converted from a PDF?

Can I see the source file to try and reproduce?  If you take a copy of the DOCX, delete all the content apart from some of the sentences that behave this way, does the problem still occur with that small sample?

In this case I have both: converted files and Word documents that were created from scratch.
I just created a sample text in Word and tried again, but it still does the same thing.

I purposely wrote "lve" instead of "love", corrected it and it still shows the underline.

Melanie J. Delgado Phillips 

I have tried to reproduce this and I can't.  Every change I correct immediately removes the red underline.  So I don't think this is a general issue, but it might be related to you working through Parallels on a MAC.  Can you try these tests?  All steps are non-destructive and easy to test.

Force a redraw inside Studio

After correcting a misspelt word, try the following:

1. Click into another segment, then return.
2. Scroll the corrected segment completely off-screen, then back.

If the underline disappears, the problem could be a UI redraw lag.

Disable Parallels "Coherence Mode"

If you are running Studio in Coherence Mode try switching to a normal windowed VM.

If the underlines now refresh reliably, the issue could be Parallels’ display abstraction interfering with WPF (that Trados Studio uses) rendering.

Disable Retina/Hi-DPI scaling for the VM

In Parallels:

• Preferences > Hardware > Graphics > Disable “Best for Retina display”.
• Restart the VM.

If this fixes the problem, the cause is also possibly due to a WPF text-rendering refresh bug triggered by Parallels’ DPI scaling.

Temporarily disable Parallels clipboard integration

In Parallels:  Actions > Configure > Options > Sharing > Disable "Share Mac clipboard".

If underlines now update correctly, the issue might be Parallels' clipboard handler interrupting Word’s real-time proofing events.  You can re-enable it afterwards.

Test CPU and RAM allocation

Ensure the VM has at least:

• 4 CPU cores
• 8-16 GB RAM
• Hypervisor set to Apple or Parallels (not automatic).

Then restart.  If the behaviour improves, the issue could have been COM proofing events being deprioritised due to low VM resources.

Create a brand-new Word document inside the VM

Inside Windows/Word (not using a Mac-synced folder):

1. Create a new blank DOCX.
2. Type a simple misspelt word ("lve").
3. Correct it.
4. Import into Studio.

If underlines refresh normally then the issue might be caused by shared folders, not Parallels generally.  If underlines still refuse to refresh then it might be caused by Parallels itself (COM or UI & timing).

Disable Parallels Shared Folders

In the VM:

• Map a native Windows folder (e.g. `C:\Users\username\Documents`).
• Save all project files there instead of `\\Mac\Documents`.

If spell-check refresh starts behaving correctly, shared-folder latency might be the cause.  Studio and Word respond far more reliably when working in native NTFS rather than Parallels’ network file system.

That's it!

I would have added a test to validate on a windows machine, but I have already confirmed the problem doesn't appear then, and I think we'd see a lot more complaints in these forums if it did.

Once you've done this the hope is we'll at least know if the root cause is likely to be one of these things:

• WPF redraw issues (apparently very common under Coherence and Retina scaling)
• Parallels clipboard/input interference
• Shared folder timing delays
• VM performance throttling

I know it seems like a lot of tests, but given your environment, that isn't the most appropriate one for running Trados Studio, it would be useful to try and rule out the likely culprits, or at least identify where the problems might be coming from so we can see if they can be fixed or not.