Please first disable Relevanssi and/or your custom code added to this View to see if they cause the issue.
If disabling Relevanssi seems to fix the problem, re-enable it and disable Views instead.
Then try searching for the phrase directly, like so:
<em><u>hidden link</u></em>
If that doesn't return the expected results then you have a problem with Relevanssi and should review its settings, and if needs be seek support from them.
Otherwise, let me know the results of the above and we can continue here.
Yes, so the issue is not with Toolset it is with Relevanssi.
You can confirm that by enabling Relevanssi, disabling Views and using the standard WordPress search, e.g.
<em><u>hidden link</u></em>
Because you are just searching against post titles you should be able to disable Relevanssi as well and WordPress search should show the posts with 'logg' in the titles (or body).
In which case it is definitely an issue you should be raising with Relevanssi.
We tried by deactivating views and relevanssi plugin and it is giving results. then I activated views plugin still its giving results.
So, issues is related to relevanssi.