Having had this problem with Phone Linka year ago and having solved the problem by cleaning up my phone records, I believe the primary issue here is a data issue. My phone contact data had been corrupted and had many duplicates across several contact databases including Office365 Exchange, google, and Samsung phone. After cleaning these databases and removing conflicts, this app started working again and has since worked reliably and repeatably.
My database was around 2500 contacts and after the duplication caused by a conflict between Microsoft and Samsung had over 20,000 contacts, mostly duplicates. Cleaning the corrupted contacts and consolidating to a single exchange database fixed the problem.
Note: I did not set out to fix the Phone Link issue although repairing the databases did resolve the Phone Link issue. I took me nearly 6 months to perform the cleanup since the duplication was not predictable and left many partial contact records forcing an almost entirely manual solution.