The claims, which are being brought by solicitors Anthony Philip James & Co (APJ), relate to investments between 2013 and 2016, in unregulated schemes such as Ethical Forestry and Global Plantations.
The claims have been submitted and accepted by the courts.
There is now a four month period in which the solicitors can notify and liaise with Guinness Mahon.
The claimants argue Guinness Mahon worked with introducers to facilitate Sipp investments into non-standard assets they claim were unsuitable for their needs.
Guinness Mahon has been contacted for comment.
The FCA has stated in a submission to the upcoming Sipp provider Berkeley Burke's judicial review that acquiring the assets in a Sipp forms part of operating the Sipp.
Under section 22 of the Financial Services and Markets Act 2000 establishing and operating a Sipp as well as buying and selling securities are regulated activities, therefore principles two and six apply.
Principle two states Sipp operators must conduct their business with "skill, care and diligence" while principle six requires providers to "pay due regard to the interests of its customers and treat them fairly".
APJ is also representing claimants against Berkeley Burke as well as other Sipp providers.