Link OnAfterFix generates a Warning writing to a network drive, but the write has succeeded

**Describe the bug**
Link OnAfterFix generates a Warning writing to a network drive, but the write has succeeded

**To Reproduce**
No repro, customer reports it happens about 5% of the time.

**Desktop (please complete the following information):**
- OS: Windows
- APL version: 18.2.45405 64-bit Unicode
- `⎕SE.Link.Version`: 3.0.19

**Additional context**
Morten has said: I suspect that the problem is that the editor itself has just written the file, and then Link “OnAfterFix” tries to determine whether it needs to update the file (does the file exist / does it have the same contents), but for some reason the file is briefly in a state where the checks that it is performing produce confusing / conflicting results.

I suppose we could put in some kind of retry / delay.