Classical/Piano genre not distributed to streaming sites

Recently I uploaded some of my live piano improvisations to various online music distributors. And I got a surprising result: classical piano music is not being accepted for streaming at several sites. 

I got this note from Soundrop that my newest "Long Piano Fantasy" "was determined to be ineligible for delivery to Automated Claiming Services". 

I checked their reasons given on the reasons for this, which they explain here: https://support.soundrop.com/hc/en-us/articles/360037548231-What-Is-Eligible-for-Automated-Claiming

Surprisingly to me, it is stated that "Piano-only instrumentals" are ineligible for this. WHY????

Another similar experience with MusicDiffusion: Several of the selected distribution channels do not accept classical piano:

• Beatport
• Facebook
• iTunes / Apple Music
• YouTube Audio Content ID

Again, why is this???