I'm not really comfortable with this since the whole idea of moving to Sailfish is to keep the own privacy... but in this case I will do it anyway to help to find a solution. Since I am not familiar with linux I am not sure which information might be sensitive in this huge amount of output. I deleted some lines - please tell me immediately if I overlooked something. So I entered "dmesg | tail", inserted the 128GB card and entered "dmesg". Attached you will find the result. I very much appreciate the help of the community. But because I'm drowning in work this will be my last post for the next days - but I am eagerly watching the search for a solution... Thank you all!
[ 1.352682] mmc1: sdhci_msm_execute_tuning: no tuning point found [ 2.092511] mmc1: sdhci_msm_execute_tuning: no tuning point found [ 2.830979] mmc1: sdhci_msm_execute_tuning: no tuning point found [ 3.572068] mmc1: sdhci_msm_execute_tuning: no tuning point found [ 4.322034] mmc1: sdhci_msm_execute_tuning: no tuning point found [ 4.361204] mmc1: mmc_sd_init_card() failure (err = -5)