I know others will disagree but why not go with Winnebago's recommended sealants? In most cases, for roof penetrations and seams the part number will cross-reference to Manus 75 AM, which is available on Amazon and elsewhere. Here's the link to some info:
Also, watch this video for some more information:
And, remember that not all silicone sealants are equal. It sounds like your's was sealed using an inappropriate sealant.
Dicor must have the best brand recognition name in the RV world. Winnebago uses Dicor on it's rubber roofed TTs but not on it's fiberglass roofed MHs. It won't damage the roof but isn't necessarily the best product to use, especially if adhesive qualities are important, such as the edges of Winnebago roofs where they are inserted into the aluminum channel.