I have connected to attiny85 MISO pin a 680 ohm resistor in serial with NPN transistor base on a personal board
And I cannot read the fuse or program an attiny85
I use arduino as isp or usbasp to program and have the same problem with both programmers. Attiny85 and arduino ISP are supplied with 5V
If I remove the 680 resistance the read of the fuse and flashing is ok
I would not expect that could disturb the flashing, is it normal ?