That's strange! If you're on windows, would you mind downloading the debug build I just added, and try running the 'Tiny-Chess-Bots.console.exe'? Would love to hear if you get any error messages in the console when trying to play against the bots that don't work (and if so could you please paste them here).
The same mistake "Input string was not in a correct format." with multiple bots when they start thinking:
ERROR: System.FormatException: Input string was not in a correct format. at System.Number.ThrowOverflowOrFormatException(ParsingStatus status, TypeCode type) at System.Double.Parse(String s) at TinyOpeningBook.<>c.<trygetmove>b__3_0(String s) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\TinyOpeningBook.cs:line 23 at System.Linq.Enumerable.SelectArrayIterator`2.ToArray() at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source) at TinyOpeningBook.TryGetMove(Board board, Double randomlyDontUseBookProb) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\TinyOpeningBook.cs:line 23 at auto_Bot_70.Bot_70.Think(Board board, Timer timer) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\chess-challenge\Bots\Bot_70.cs:line 128 at BotRunner.NotifyTurnToMove(Board board) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\BotRunner.cs:line 35 at GameManager.NotifyTurnToMove() in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\GameManager.cs:line 187 at GameManager.OnMoveChosen(Move move) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\GameManager.cs:line 162 at HumanPlayer.ChoseMove(Move move) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\HumanPlayer.cs:line 212 at HumanPlayer.TryMakeMove(Coord startSquare, Coord targetSquare) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\HumanPlayer.cs:line 201 at HumanPlayer.HandlePiecePlacement(Vector2 mousePos) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\HumanPlayer.cs:line 113 at HumanPlayer.HandleDragMovement(Vector2 mousePos) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\HumanPlayer.cs:line 85 at HumanPlayer._Process(Double delta) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\scripts\application\HumanPlayer.cs:line 62 at Godot.Node.InvokeGodotClassMethod(godot_string_name& method, NativeVariantPtrArgs args, godot_variant& ret) at HumanPlayer.InvokeGodotClassMethod(godot_string_name& method, NativeVariantPtrArgs args, godot_variant& ret) in C:\Users\sebas\Desktop\Sebastian\Projects\Chess\Chess Challenge\Tiny-Chess-Godot\Godot.SourceGenerators\Godot.SourceGenerators.ScriptMethodsGenerator\HumanPlayer_ScriptMethods.generated.cs:line 73 at Godot.Bridge.CSharpInstanceBridge.Call(IntPtr godotObjectGCHandle, godot_string_name* method, godot_variant** args, Int32 argCount, godot_variant_call_error* refCallError, godot_variant* ret) at: godotsharp_pusherror (modules/mono/glue/runtime_interop.cpp:1324)</trygetmove>