TextMeshPro 2.0.1 error

Hello, my fellow game devs!
I'm quite new in using TextMeshPro and so after a long and tedious fight with this package and his two mighty problems, I finally ask you for your's generous help.
First trouble is this big error message that now I'm seeing every time opening my project and also in my nightmares. After a long, painful and worthless solution-seeking I just give up on it, leaving as it is, because only trouble it makes - just bothering me, sitting in the console as an ugly weed in a beautiful garden of my debug's logs. But this hideous monstrosity may be the cause of the second and worse problem, so I put his text here:

 ArgumentException: An item with the same key has already been added. Key: 0
 System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) (at <a8ed250850854b439cedc18931a314fe>:0)
 System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) (at <a8ed250850854b439cedc18931a314fe>:0)
 TMPro.TMP_FontAsset.InitializeDictionaryLookupTables () (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMP_FontAsset.cs:589)
 TMPro.TMP_FontAsset.ReadFontAssetDefinition () (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMP_FontAsset.cs:607)
 TMPro.TMP_FontAsset.get_characterLookupTable () (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMP_FontAsset.cs:139)
 TMPro.TextMeshProUGUI.LoadFontAsset () (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:539)
 TMPro.TextMeshProUGUI.OnValidate () (at Library/PackageCache/com.unity.textmeshpro@2.0.1/Scripts/Runtime/TMPro_UGUI_Private.cs:302)

And now, the second problem. This beast is stealing my time every time I open my future masterpiece to breath some life inside of it. Every time I start to work on my dream project one or more of many TextMeshProUGUI just stops displaying text carefully placed in it! The text is still inside the text window, but the inside scene and game view - nothing, like it were stolen by a ghost or some other supernatural thing. I thought the problem was inside SDF Material attached to the object, but, what a surprise, it also disappears like a bad father, when it goes to buy some cigarets and then never returns. The only solution I found for that - create a new TextMeshPro text object, but, as you might already guess, this is not permanent.

Thanks for your time and mind power to help me defeat this annoying duo. Also, I will provide additional information, but I do not know what type of information is needed and where to seek.
Have a nice day!