Bug: HR data issue (low value and sampling rate) for custom made apps

Hello, 

This is a follow up to problem described here: https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/369676/low-hr-rate-recorded-during-activity

In general I recently noticed lower HR values coming from Fenix7 + graph looked like the sampling rate is low (1/couple of seconds). Tooday I investigated this issue:

1. I started my tooday workout using default Tennis  activity (Fenix7, CIQ 5.0.0, FW16.22) and hearrt rate was looking fine (first picture in comments):

Here is a *.fit file in csv format for reference: https://www.tennis-ai.net/2024-04-30-20-00-20.csv

2.Then after I saw everything is fine I saved activity, run Tennis AI app (my app available in the store) and recorded next couple of minutes with the same workout paste - HR was just keep droping down (second picture in comments):

What you can notice is that graph is 'stepped' as if the sampling rate was reduced.

Here is a *.fit file in csv format for reference:https://www.tennis-ai.net/2024-04-30-20-15-10.csv

No updates were done recently to my app. I was trying to restart watch, change HR sampling from to smart and back to frequent, reinstall Tennis AI app etc. but it is still looking like this. Fortunately none of my users has reported this issue to me yet but it looks like just a matter of time to start getting negative feedback.

I would love anyone to let me know if this issue is related to Garmin, my code, my watch model or any other clue that I could follow up with.

Thanks in advance